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18 Aug 2018, 09:36
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let s10 s6 and s4 be the sums of first 10, 6 and last 4 days respectively.
s10 = 400*10 = 4000
s6 = 6*360 =2160
s4 = s10 - s6 = 4000 - 2160
s4 = 1840
so Average of last 4 days is 1840/4 = 460
Answer D
s10 = 400*10 = 4000
s6 = 6*360 =2160
s4 = s10 - s6 = 4000 - 2160
s4 = 1840
so Average of last 4 days is 1840/4 = 460
Answer D
11 Jun 2020, 01:23
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pzazz12
This can be solved using Weighted Average concept also.
First, let's make an observation based on the given data. Average revenue of 10 days is $400 while the average revenue of first 6 days is $360, $40 less than average of 10-day period. For average revenue of first 6 days, $360, to go up to average revenue of $400 overall, the average revenue of remaining 4 days must be >$400 since the number of days left are lesser.
So, here no. of days act as weights.
Now, weighted average is calculate using the formula:
Avg. = (W1* X1 + W2*X2)/W1+W2 ---------------------- 1 ; where W1, W2 = weights ; X1, X2 = values
If you rearrange the formula in "1" you get,
W1/W2 = (X2 - Avg)/(Avg - X1) ---------- 2
Applying formula "2" in the given question, we have
w1 = 6 (days)
w2 =4 (days)
Avg = $400
X2 = a (unknown - to be calculated)
X1 = $360
Substituting values, we get
6/4 = (a - 400)/ (400-360) or 3/2 = (a-400)/40
on simplifying, we get
60 = a-400 or a = 400 + 60 = $460
So, the snack shop must make an average revenue of $460 in last 4 days in order to have overall average revenue of 10-days equal to $400
02 Feb 2021, 14:49
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Hi,
This problem can be solved in 30 seconds using weighted averages coupled with the base point method :
the 6 days account for 3/5 of the 10 days and the remaining 4 days for 2/5
let's take 400 as a base point
360 is -40 from our base
3/5*-40+2x/5 =0
(-120+2x)/5=0
0=-120+2x
120=2x
x=+60
Add +60 to our base point of 400, we get 460$
Answer D)
This problem can be solved in 30 seconds using weighted averages coupled with the base point method :
the 6 days account for 3/5 of the 10 days and the remaining 4 days for 2/5
let's take 400 as a base point
360 is -40 from our base
3/5*-40+2x/5 =0
(-120+2x)/5=0
0=-120+2x
120=2x
x=+60
Add +60 to our base point of 400, we get 460$
Answer D)
