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by Shahrukh_mbabreakspace » Wed Jul 04, 2018 2:21 am
Average= Sum of all bills/7
Sum of all bills = 511
Average = 511/7= 73

Alternatively,
If we assume average to 70 and just look at the distortions and then just edit the answer:
So it becomes(+4-1-6+9-6+14+7)= 21
21/7=3

70+3=73

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by Brent@GMATPrepNow » Wed Jul 04, 2018 6:25 am
BTGmoderatorDC wrote:Over the past 7 weeks, the Smith family had weekly grocery bills of $74, $69, $64, $79, $64, $84, and $77. What was the Smiths' average (arithmetic mean) weekly grocery bill over the 7-week period?

A. $64

B. $70

C. $73

D. $74

E. $85
Average = ($74 + $69 + $64 + $79 + $64 + $84 + $77)/7
= $511/7
= $73

Answer: C

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by Scott@TargetTestPrep » Sun Jul 22, 2018 5:43 pm
BTGmoderatorDC wrote:Over the past 7 weeks, the Smith family had weekly grocery bills of $74, $69, $64, $79, $64, $84, and $77. What was the Smiths' average (arithmetic mean) weekly grocery bill over the 7-week period?

A. $64

B. $70

C. $73

D. $74

E. $85
We can determine the average using the formula: average = sum/quantity:

average = (74 + 69 + 64 + 79 + 64 + 84 + 77)/7 = 511/7 = 73

Answer: C

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by regor60 » Mon Jul 23, 2018 5:23 am
BTGmoderatorDC wrote:Over the past 7 weeks, the Smith family had weekly grocery bills of $74, $69, $64, $79, $64, $84, and $77. What was the Smiths' average (arithmetic mean) weekly grocery bill over the 7-week period?

A. $64

B. $70

C. $73

D. $74

E. $85
Just add up the one's digits and keep track the running sum's one's digit.

Final one's digit is a 1. Since the overall sum is divisible by 7, the average must end in 3. The only answer that meets this is C, 73
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