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by beat_gmat_09 » Sun Nov 28, 2010 4:06 am
A new cell phone plan is offering pricing based on average monthly use. Brandon and Jodie are comparing their average use to determine the best plan for them. Brandon's average monthly usage in 2001 was q minutes. Was this less than, greater than, or equal to Jodie's 2001 average monthly usage, in minutes?

(1) From January to August 2001, Jodie's average monthly usage was 1.5q minutes.

(2) From April to December 2001, Jodie's average monthly usage was 1.5q minutes.
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Source: — Data Sufficiency |
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by rishab1988 » Sun Nov 28, 2010 5:16 am
Answer should be B

Brandon's average monthly usage for 12 months =q.
Total usage for 12 months = 12q

Since time period of usage for both Brandon and Jodie is same,we simply need to compare their cumulative usage for 12 months.We will automatically get average by dividing with 12.

So the rephrased question is "Is Jodie's cellphone usage for 2001 greater than,equal to,or less than 12q minutes"

1) Jan- August avg =1.5 q minutes.

Jan-Aug=8 months

Reason : Jan and August are inclusive and [August(8th month)-January (1st month)]=7.But since it is inclusive we have to add 1 to give 7+1=8

Total usage for 8 months = 1.5*8q= 12q.

Since,there is no info for the remaining months,the usage for all remaining months could be 0,in which case Jodie's total usage for 2001 would be 12q [answer would be equal to]

But if the minutes used by Jodie in each of the 4 months is q minutes,then the total usage =12q+4q=16q [greater than]

Insufficient.

2) April-December= 9 months

Each month usage = 1.5 q

Total usage =1.5*9q=13.5q.

Since,even if the value of usage in first 3 months is 0,the total usage of Jodie is greater than Brandon.Therefore,we can say that the average usage of cellphone by Jodie is greater than Brandon.

Hence B is the answer.

[Duration for which cellphone is used cannot be negative!]

What is the OA?
Last edited by rishab1988 on Sun Nov 28, 2010 5:18 am, edited 1 time in total.
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by beat_gmat_09 » Sun Nov 28, 2010 5:18 am
You got it, B.
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by Anaira Mitch » Sat Dec 10, 2016 7:06 am
Is there any other way to do this problem?
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by [email protected] » Sat Dec 10, 2016 1:10 pm
Hi Anaira Mitch,

You can answer this question by TESTing VALUES.

We're told that Brandon's average monthly usage is Q minutes. We're asked if this number is less than, greater than or equal to Jodie's average monthly usage.

1) From January to August 2001, Jodie's average monthly usage was 1.5q minutes.

IF....
Brandon's average monthly usage is 1 minute per month, then he totals 12(1) = 12 minutes for the year.
From January to August, we have 8 months, so Jodie's usage would be 8(1.5) = 12 minutes. However, we don't know how many minutes she used for the last 4 months of the year.

IF...
Jodie averaged 0 minutes per month for each of the last 4 months, then her total for the years would be 12+0 = 12 minutes and the two values are EQUAL
Jodie averaged 1 minutes per month for each of the last 4 months, then her total for the years would be 12+4 = 16 minutes and Brandon's average is LESS than Jodie's.
Fact 1 is INSUFFICIENT

2) From April to December 2001, Jodie's average monthly usage was 1.5q minutes.

IF....
Brandon's average monthly usage is 1 minute per month, then he totals 12(1) = 12 minutes per year.
From April to December, we have 9 months, so Jodie's usage would be 9(1.5) = 13.5 minutes. At this point, Jodie has already used MORE minutes than Brandon for the year, so her average will automatically be higher than Brandon's (regardless of how many minutes she used in the first 3 months of the year). The answer to the question is ALWAYS LESS.
Fact 2 is SUFFICIENT

Final Answer: B

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by Mo2men » Sun Jun 10, 2018 1:03 pm
[email protected] wrote:Hi Anaira Mitch,

You can answer this question by TESTing VALUES.

We're told that Brandon's average monthly usage is Q minutes. We're asked if this number is less than, greater than or equal to Jodie's average monthly usage.

1) From January to August 2001, Jodie's average monthly usage was 1.5q minutes.

IF....
Brandon's average monthly usage is 1 minute per month, then he totals 12(1) = 12 minutes for the year.
From January to August, we have 8 months, so Jodie's usage would be 8(1.5) = 12 minutes. However, we don't know how many minutes she used for the last 4 months of the year.

IF...
Jodie averaged 0 minutes per month for each of the last 4 months, then her total for the years would be 12+0 = 12 minutes and the two values are EQUAL
Jodie averaged 1 minutes per month for each of the last 4 months, then her total for the years would be 12+4 = 16 minutes and Brandon's average is LESS than Jodie's.
Fact 1 is INSUFFICIENT

2) From April to December 2001, Jodie's average monthly usage was 1.5q minutes.

IF....
Brandon's average monthly usage is 1 minute per month, then he totals 12(1) = 12 minutes per year.
From April to December, we have 9 months, so Jodie's usage would be 9(1.5) = 13.5 minutes. At this point, Jodie has already used MORE minutes than Brandon for the year, so her average will automatically be higher than Brandon's (regardless of how many minutes she used in the first 3 months of the year). The answer to the question is ALWAYS LESS.
Fact 2 is SUFFICIENT

Final Answer: B

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Rich
Dear Rich,

Based on you testing values, why did not you consider q=zero?
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by nitesh50 » Wed Dec 12, 2018 12:58 am
Hi

Can any expert explain that why can't we assume q to have a non integer value?
It that had been the case, the answer should have been E.
Since q may be any number we can;t conclusively conclude that B is sufficient?
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