Let the number of days Terry read at 75 pages/days be x.
Then the total number of pages = 75x + 690 and
The toal number of days Terry took to complete the assignment = x+6
But from the first statement of the question stem. The total number of pages = 90*(x+6)
Since total number of pages in both the cases is equal 75x + 690 = 90x + 540. So 15x = 150 and x = 10.
Total number of days required = x+6 = 10+6 = 16

wied81 wrote:From OG #119 - Problem solving:

119) In order to complete a reading assignment on time, Terry planned to read 90 pages per day. However, she read only 75 pages per day at first, leaving 690 pages to be read during the last 6 days before the assignment was to be completed. How many days in all did Terry have to complete the assignment on time?

A) 15

B) 16

C) 25

D) 40

E) 46

OA: B

We can plug in the answers, which represent the total number of days.
Since the planned rate was 90 pages per day, the total number of pages must be a multiple of 10.
Over the last 6 days, the total number of pages read = 690.
Thus, the total number of pages read at a rate of 75 pages per day must be a multiple of 10.
Answer choice A (15 days) implies 9 days at 75 pages per day.
Answer choice C (25 days) implies 19 days at 75 pages per day.
Neither of these answers will yield a total number of pages that is a multiple of 10.
Eliminate A and C.

Answer choice B: 16 days
10 days at 75 pages per day + 690 pages over the last 6 days = 10*75 + 690 = 1440.
16 days at 90 pages per day = 16*90 = 1440.
Success!

The correct answer is B.

wied81 wrote:From OG #119 - Problem solving:

119) In order to complete a reading assignment on time, Terry planned to read 90 pages per day. However, she read only 75 pages per day at first, leaving 690 pages to be read during the last 6 days before the assignment was to be completed. How many days in all did Terry have to complete the assignment on time?

A) 15

B) 16

C) 25

D) 40

E) 46

OA: B

Solution:

We can solve this problem in a similar manner to the way we'd solve a work problem, and we can use a table to organize our information. We can fill in what she was "supposed" to do and what she "did" do.

Let's define T as the number of days to complete the reading assignment. Since we are given that her initial plan was to read 90 pages per day, we can multiply 90 and T, getting 90T for the total work that was supposed to be done for the entire reading assignment.

We are next told that she actually started by reading 75 pages per day until she had 6 days left to finish the project. Since T represents the total number of days, we can say she read 75 pages per day for (T-6) days. When we multiply, we see that her work done on the T-6 days was 75T-450. Finally, we see that she read a total of 690 pages in the final 6 days, which is an average of 115 pages per day.

We summarize all of this information in a table, using the work formula: Work = rate x time.



We can now use the work equation to equate what she planned to do to complete the assignment and what she actually did.

Planned = Did (part 1) + Did (part 2)

90T = (75T - 450) + 690

15T = 240

T = 16

Answer:B

let number of days = d

d*90 = 75(d-6) + 690
solve for d
90d-75d = 690-450
15d = 240

d=16
number of days required =16