A certain plumber charges $92 for each job completed

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A certain plumber charges $92 for each job completed in 4 hours or less and $23 per hour for each job completed in more than 4 hours. If it took the plumber a total of 7 hours to complete two separate jobs, what was the total amount charged by the plumber for the two jobs?

(1) The plumber charged $92 for one of the two jobs.
(2) The plumber charged $138 for one of the two jobs.

Official Guide question
Answer: B

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by Brent@GMATPrepNow » Tue Aug 01, 2017 10:21 am

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jjjinapinch wrote:A certain plumber charges $92 for each job completed in 4 hours or less and $23 per hour for each job completed in more than 4 hours. If it took the plumber a total of 7 hours to complete two separate jobs, what was the total amount charged by the plumber for the two jobs?

(1) The plumber charged $92 for one of the two jobs.
(2) The plumber charged $138 for one of the two jobs.

Official Guide question
Answer: B
Target question: What was the total amount charged by the plumber for the two jobs?

Given: $92 for each job completed in 4 hours or less. $23 per hour for each job completed in more than 4 hours. Total work time was 7 hours

Statement 1: The plumber charged $92 for one of the two jobs
This statement doesn't FEEL sufficient, so I'll TEST some values.
There are several scenarios that satisfy statement 1. Here are two:
Case a: the plumber spent 1 hour on one job (and received $92) and spent 6 hours on the other job (at $23/hours). In this case, the TOTAL amount charged = $92 + (6)($23) = $230
Case b: the plumber spent 2 hours on one job (and received $92) and spent 5 hours on the other job (at $23/hours). In this case, the TOTAL amount charged = $92 + (5)($23) = $207
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Aside: For more on this idea of plugging in values when a statement doesn't feel sufficient, read my article: https://www.gmatprepnow.com/articles/dat ... lug-values

Statement 2: The plumber charged $138 for one of the two jobs.
This means the plumber MUST have spent more than 4 hours on this job
So, the rate charged is $23/hour
$138/23 = 6. So, the plumber spent 6 hours on this job (and received $138), which means he spent 1 hour on the other job (and received $92)
So, the TOTAL amount charged = $138 + $92 = $230
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

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by Jeff@TargetTestPrep » Wed Aug 09, 2017 11:12 am

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jjjinapinch wrote:A certain plumber charges $92 for each job completed in 4 hours or less and $23 per hour for each job completed in more than 4 hours. If it took the plumber a total of 7 hours to complete two separate jobs, what was the total amount charged by the plumber for the two jobs?

(1) The plumber charged $92 for one of the two jobs.
(2) The plumber charged $138 for one of the two jobs.

Official Guide question
Answer: B
We are given that a certain plumber charges $92 for each job completed in 4 hours or less and $23 per hour for each job completed in more than 4 hours. We are also given that it took the plumber a total of 7 hours to complete two separate jobs, and we need to determine the total amount charged by the plumber for the two jobs.

Statement One Alone:

The plumber charged $92 for one of the two jobs.

We see that the job he charged $92 could be 1, 2, 3, or even 4 hours long, which means the other job was 6, 5, 4, or 3 hours, respectively. Thus, we cannot determine the total amount charged for the two jobs. Statement one alone is not sufficient to answer the question.

Statement Two Alone:

The plumber charged $138 for one of the two jobs.

We see that the job he charged $138 must be longer than 4 hours. Since he charges $23 per hour for a job that is longer than 4 hours, we have:

138 = 23(number of hours)

6 = number of hours

Thus, the other job must have taken 1 hour and cost $92. The two jobs will cost a total of $138 + $92 = $230. Statement two is sufficient to answer the question.

Answer: B

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by [email protected] » Tue Mar 27, 2018 2:56 pm

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Hi All,

We're told that a certain plumber charges $92 for each job completed in 4 hours or LESS and $23 PER HOUR for each job completed in MORE than 4 hours and that it took the plumber a total of 7 hours to complete two separate jobs. We're asked for the total amount charged by the plumber for the two jobs. This question can be solved by TESTing VALUES.

1) The plumber charged $92 for one of the two jobs.

Fact 1 tells us that 1 of the jobs was 4 hours OR LESS. However, we don't know exactly how long that one job took, so we don't know how long the OTHER job took (and how much that other job cost).

IF.....
The first job was 3 hours and the second job was 4 hours, then the total charged would be $92 + $92 = $184
The first job was 2 hours and the second job was 5 hours, then the total charged would be $92 + $115 = $207
Fact 1 is INSUFFICIENT

2) The plumber charged $138 for one of the two jobs.

Since $138 is more than $92, that one job clearly took MORE than 4 hours. By extension, the second job would have taken LESS than 7 - 4 = 3 hours and we KNOW that the second job would have cost $92. Thus, the total charged MUST have been $138 + $92 = $220.
Fact 2 is SUFFICIENT

Final Answer: B

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