M40-122

Question

Riley was assigned a task to type a document. Was Riley's average (arithmetic mean) typing rate more than 80 words per minute during the task?

(1) Riley took less than 45 minutes to complete the task.
 
(2) The document contained less than 3,600 words.

Bunuel · Answer

Official Solution:

Riley was assigned a task to type a document. Was Riley's average (arithmetic mean) typing rate more than 80 words per minute during the task? 
 
(1) Riley took less than 45 minutes to complete the task.
 
Clearly not sufficient.
 
(2) The document contained less than 3,600 words.
 
Clearly not sufficient.
 
(1)+(2) Together, we know that Riley typed fewer than 3,600 words in less than 45 minutes. This is not enough to determine whether the average rate was above 80 words per minute. For example, if Riley typed 3,000 words in 30 minutes, the rate would be 100 words per minute; if 300 words in 30 minutes, the rate would be 10 words per minute. Not sufficient.
 
Answer: E

anushree01 · Answer

I had a doubt - 
If a<10, b<20 and we are told that c = a/b
then will c<10/20 --> c<1/2 ???

Just wanted to validate, this isn`t correct, right ?

Bunuel · Answer

No, that is not correct. From a < 10 and b < 20, you cannot conclude that a/b < 10/20, because putting separate upper bounds on the numerator and denominator does not fix an upper bound on the ratio. For example, if a = 9 and b = 1, then a/b = 9, which is not less than 1/2.

anushree01 · Answer

That`s really helpful to keep as a rule of the thumb.
Thanks again!!

M40-122

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