Bunuel 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.
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 the plumber charged for the two jobs.
Statement One Alone:
The plumber charged $92 for one of the two jobs.
We see that the job for which 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 for which 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, with a cost of $92. The two jobs will cost a total of $138 + $92 = $230. Statement two is sufficient to answer the question.
Answer: B
What I don't understand is he could have charged $138 in 2 ways :
1. if he worked for
1.5 hours then he will charge 92*1.5= 138 so for remaining 5.5 hrs he charged 23*5.5= 126.5 . so total charged amount will be 138+126.5=264.5$
2. he worked for 6 hrs and charged 23*6= 138 and for next 1 hr he charged 92$ so total charged amount is 92+138= 230$ .... so we are not getting any unique answer so how come statement b alone is sufficient??????