Seven questions for christoph!

q= 4x5n=20n
so the ratio of q:n=20n:n or 20:1

[Question 1]

There's a square glass. To paint this glass, it costs $8 per square meter. To paint its circumference, it costs $10 per meter. If the total cost of painting the glass and the total cost of painting its circumference are the same, what is the area of this glass?



Ans: The area of glass = 25


Lets say a is the side of the square

To paint glass, $8, i.e 8a^2
To paint circumference, $1, ie 4a * 10 = 40a

Now these are equal, so 8a^2 = 40a, solving a = 5
The area = a^2 = 25

Sorry for the confusion, Bhai. I edited question 4. And please double-check question2.

[Question 1]

There's a square glass. To paint this glass, it costs $8 per square meter. To paint its circumference, it costs $10 per meter. If the total cost of painting the glass and the total cost of painting its circumference are the same, what is the area of this glass?

25

Let side of square = x
Cost of area painting = 8*x^2
Cost of circumfrence painting = 10 * 4x

8* x^2 = 40 x so x = 5 Area = 25

[Question 2]

Is (a+5)^4 < (b-5)^4 ?

1) a+b > 5
2) a > b

C

St 1: Let a = 5 and b = 4 then stem eq is FALSE
Let a = 10 and b = -4 then stem eq is FALSE
Let a = -4 and b = 10 then stem eq is TRUE

so INSUFF

St2: Let a = 4 and b = 3 then stem eq is FALSE
Let a = -3 and b = -4 then stem eq is TRUE

So INSUFF

Combined St1 and St2: Take same examples and its always FALSE
So SUFF
[Question 3]

John has 25 cent coins and 5 cent coins. The number of 25 cent coins are four times as many as that of 5 cent coins. What is the ratio of the total value of 25 cent coins to the total value of 5 cent coins?

20:1

25 cents coins = x
5 cents coins = y

x= 4y

Total value of 25 cents coins = 25x
Total value of 5 cents coins = 5y
Ratio = 25x/5y = (25 * 4y)/y = 20:1

[Question 4]

A set is consisted of consecutive integers. The smallest element and the largest element are even. The number of even elements in this set is 7. When you pick one out of this set, what is the probability of picking an even number?

7/13

When first and last elements are even in a series of consecutive integers then there will be 6 odd integers in the whole series. So prob = 7/13

[Question 5]

The sum of 1, 2, 6, and 24 is a multiple of a prime number. What is the sum of the prime numbers?

3+11 = 14
[Question 6]

A car runs at 80 km/hour. How many seconds does it take for this car to run 400 meters?

(3600 * 400)/80000 = 18

[Question 7]

Either 6 or 24 ornaments are put into boxes. If the total number of these ornaments are 126, what are the number of boxes with 6 ornaments and boxes with 24 ornaments?

1) There are less than 4 boxes with 6 ornaments.
2) There are more than 3 boxes with 24 ornaments.

A

Eq from stem is

6x + 24y =126

St1: When x < 4 then x is either 1,2 or 3. Only x = 1 leads to integer value of y in above equation . So x =1 and y = 5. So SUFF

St2: When y > 3 then y is either 4 or 5 (greater values will not fit in above equation). y = 4 leads x = 5 and y = 5 leads x = 1. So INSUFF.

I agree with all your answers