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Question: What is the average price of all the items on the rack?
Let a, b, c, d, e be row indicators and 1,2,3,4,5,6,7,8 be the column indicators

Given that:
X1 = (a1+a2+a3+....+a8)/8
X2 = (b1+b2+b3+....+b8)/8
X3=(c1+c2+c3+....+c8)/8
X4=(d1+d2+d3+....+d8)/8
X5=(e1+e2+e3+....+e8)/8

Y1 = 1a+1b+...+1e
Y2 = 2a+2b+...+2e
.
.
.
Y8 = 8a+8b+...+8e

From Statement 1:
X1+X2+X3+X4+X5 = 850
Summing all, we have averages of all items on rack and we also know the total number of items as 8*5 = 40
So we can calculate the average price of all items
Hence sufficient

Eliminate option B, C and D
From Statement 2:
Y1+Y2+Y3+Y4+Y5 = 1360
Summing all, we have averages of all items on rack and we also know the total number of items as 8*5 = 40
So we can calculate the average price of all items
Hence sufficient

So option D is correct

Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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Statement 1:
Total = 8 (X1+X2+X3+X4+X5) as we know total price and total no of item we can find avg so Sufficient
Statement 2:
Total = 5 (Y1+Y2+Y3+Y4+Y5+....Y8) as we know total price and total no of item we can find avg so Sufficient

Hence Ans D: Each alone Sufficient
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Statement (1):
X1 + X2 + X3 + X4 + X5 = 850
Each Xₘ is the average price of 8 items in row m.
So:
Total price of each row = 8 × Xₘ
Total price of all items = 8 × (X1 + X2 + ... + X5) = 8 × 850 = 6800
Average price = Total / 40 = 6800 / 40 = 170
Statement (1) alone is sufficient

By similar logic, Statement (2) alone is sufficient

Answer D
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1) {8*(x1+x2+x3+x4+x5)}/40 = (8*850)/40 = 170
2) {5*(y1+y2+y3+y4+y5+y6+y7+y8)}/40 = (5*1360)/40 = 170

Both statements are alone sufficient
Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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We can think of a 5 * 8 matrix. For each of the row the total price will be the number of items in that row multiplied by the average price of the row and the total price if each column will be the number of items in that column multiplied by the average price if the items in that column.

(1) \(X_1 + X_2 + ... + X_5 = $850\)

Number of items in each row = number of columns = 8

Multiplying by 8 on both sides we get

\(8(X_1 + X_2 + ... + X_5) = $(850*8)\)

This will give the total price. Once we have the total price, we can get the average price of all the 40 items.

Average = Total / Number of items = 8*850/40

The statement alone is sufficient.

(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)

Number of items in each column = number of rows = 5

Multiplying by 5 on both sides we get

\(5( Y_1 + Y_2 + ... + Y_8) = $(1360*5)\)

This will give the total price. Once we have the total price, we can get the average price of all the 40 items.

Average = Total / Number of items = 1360*5 /40

The statement alone is sufficient.

Option D
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So let's rewrite what's actually being asked in the question.
We have the average (arithmetic mean) of the price of items in each row (m) = \(X_m\) [1 ≤ m ≤5]
and the average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8].
We can find the total value of all the items in Eg) Row 1 = \(X_1*8\)
And we can find the total value of all the items in column 1= \(Y_1 *5\)
So if we just add total values of all rows and divide that by 40, or total values of all columns and divide by 40, we get our reqd average price.
[1] \(X_1 + X_2 + ... + X_5 = $850\) - sufficient (multiply by 5 and divide by 40)
[2] \(Y_1 + Y_2 + ... + Y_8 = $1,360\) sufficient
Answer = D
Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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As a visual learner, I'll visualise a bookshelf with 40 books across 5 Rows, with 8 books per row all spaced equally thus making up the 8 columns. We know the range of the price per item in each row and column.

Using statement (1):
Total value of all 5 rows of books is $850. Because we have the same number of books in each row, I can divide 850 by 5 to get a total of 170 dollars per book and conclude that statement (1) alone is sufficient.

Using statement (2)
Total value of all 8 rows is $1360. Because we have the same number of books in each column, I can divide 1360 by 8 to get a total of 170 dollars per book and conclude that statement (2) alone is sufficient.

Answer: D) Each statement alone is sufficient
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Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)



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Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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As we can say the grid is something like below :
Avg Sum of the entire row
Row 1: [ A1 ] [ A2 ] [ A3 ] [ A4 ] [ A5 ] [ A6 ] [ A7 ] [ A8 ] => X1 8X1
Row 2: [ B1 ] [ B2 ] [ B3 ] [ B4 ] [ B5 ] [ B6 ] [ B7 ] [ B8 ] => X2 8X2
Row 3: [ C1 ] [ C2 ] [ C3 ] [ C4 ] [ C5 ] [ C6 ] [ C7 ] [ C8 ]
Row 4: [ D1 ] [ D2 ] [ D3 ] [ D4 ] [ D5 ] [ D6 ] [ D7 ] [ D8 ]
Row 5: [ E1 ] [ E2 ] [ E3 ] [ E4 ] [ E5 ] [ E6 ] [ E7 ] [ E8 ]

Avg : Y1 Y2 Y3 .....
Sum of
the cols : 5Y1 5Y2 5Y3.


Stmt 1 : (1) \(X_1 + X_2 + ... + X_5 = $850\)
To find the avg we need the total sum, This ca be sum of the 5 rows. 8X1+8X2+... => 8(X1+X2...)
Hence, we can find sum and avg,

Stmt 1 is sufficient.

Stmt 2 : \(Y_1 + Y_2 + ... + Y_8 = $1,360\)
Similarly we can get the sum by adding all the column totals.
5Y1+5Y2......
Hence, stmt 2 is also sufficient.

Hence IMO D
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Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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The average price of all items on the rack is the total sum of prices divided by the total number of items (40).
Average price of all items =
[ltr]
Total sum of prices/40[/ltr]

Let's evaluate the given statements:
(1) $X_1 + X_2 + \dots + X_5 = $850
From this statement, the sum of the average prices of each row is known.
The sum of the sums of prices in each row is
[ltr]
8×(X1+X2+...+X5)=8×850=6800[/ltr]
.
The total sum of prices of all 40 items is 6800.
The average price of all items =
[ltr]
6800/40=170[/ltr]
.
Therefore, statement (1) alone is sufficient to find the average price of all items.

(2) $Y_1 + Y_2 + \dots + Y_8 = $1,360
From this statement, the sum of the average prices of each column is known.
The sum of the sums of prices in each column is
[ltr]
5×(Y1+Y2+...+Y8)=5×1360=6800[/ltr]
.
The total sum of prices of all 40 items is 6800.
The average price of all items =
[ltr]
6800/40=170[/ltr]
.
Therefore, statement (2) alone is also sufficient to find the average price of all items.
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Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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40 items are arranged on a rack of 5 rows and 8 columns.

Each row has 8 values, and each column has 5 values.

The average price of items in each row is \(X_m\) [1 ≤ m ≤5]

The average price of items in each column is \(Y_n\) [1 ≤ n ≤ 8]

To find: Average price of all items. ?

Statement 1:

(1) \(X_1 + X_2 + ... + X_5 = $850\)

Average = sum / n

$850 = sum / 8. Hence, sum = 8*850 = 6800.

Average of entire rack = 6800/40 = 170

Hence, Sufficient

Statement 2:

(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)

Sum of average of column values = $1360

$1360 = Sum/ 5 . Thus, sum = $1360*5 = 6800

Average of entire rack = 6800/40 = 170

Hence, Sufficient

Option D.
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Solution:

We know that there are a total of 5 rows and 8 columns. Also, the average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8].

Statement 1

\(X_1 + X_2 + ... + X_5 = $850\) Insuffficient

We won't be able to get to a solution

Statement 2

\(Y_1 + Y_2 + ... + Y_8 = $1,360\) Insufficient

By combining both statements, we get the conclusive answer: \(\frac{Sum of all observations}{No. of observations}\)

\(\frac{850 + 1360}{40}\) = 55.25

Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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Average price = total sum / 40.
- Statement (1): \( X_1 + \cdots + X_5 = 850 \). Sum = \( 8 \times 850 = 6,800 \). Average = \( 6,800 / 40 = 170 \). Sufficient.
- Statement (2): \( Y_1 + \cdots + Y_8 = 1,360 \). Sum = \( 5 \times 1,360 = 6,800 \). Average = \( 6,800 / 40 = 170 \). Sufficient.

Answer: (D)
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1) Avg = (X1 + X2 + ... +X5)/5 = 850/5 = 170
2)Avg = (Y1 + Y2 + ... + Y8)/8 = 1360/8 = 170

Ans = D
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Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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asked : Average of all the items.

Statement 1:
sum of prices of all the averages of the rows = 850
Average of all the items = 850/ Number of rows i.e.(5)

Hence A,D

Statement 2:
sum of average prices of all the columns = 1360
Average of all the items = 850/ Number of columns i.e.(8)

Hence each statement alone is sufficient Hence D.
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C) Each is sufficient by itself.

Individual prices are not important, you need the total amount and the total number. Answer would be 850*8/40=170 or 1360*5/40=170.
Bunuel
In a store, 40 items are arranged on a rack in 5 rows and 8 columns. The average (arithmetic mean) of the price of items in each row (m) is \(X_m\) [1 ≤ m ≤5]. The average of the price of items in each column (n) is \(Y_n\) [1 ≤ n ≤ 8]. What is the average price of all items on the rack?

(1) \(X_1 + X_2 + ... + X_5 = $850\)
(2) \(Y_1 + Y_2 + ... + Y_8 = $1,360\)


 


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Condition One: X1 + X2 + ... + X5 = $850
We can rewrite the equation as
(8X1 + 8X2 + ... + 8X5) / 40 = $850 8 / 40
This yields the overall average.

Condition Two: Similarly,
(5Y1 + 5Y2 + ... + 5Y8) / 40 = $1,360 5 / 40
This also yields the overall average.

Both conditions are sufficient.
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