DH99 wrote:

Two typists P and Q work individually for 6 hours a day. What is the difference between the average number of pages typed per hour by person P on a single day and the average number of pages typed per hour by person Q on the single day?

(1) The typing speed of the person P is constant and is 10 pages per hour, whereas the typing speed of person Q is 19 pages per hour for initial three hours on the same day.

(2) Twice the average number of pages typed by person Q in one hour is 3.8 times the average number of pages typed by person P in one hour.

(1) Average of P (Pavg) is 10 but cannot deduce average of Q(Qavg) and hence the difference between the averages... Not sufficient

(2) 2 * Qavg = 3.8 * Pavg ..We do not know the value of Qavg ...Not sufficient

However when we combine

we can get the Qavg = (3.8 * 10)/2 = 19 and hence the difference between both the averages (19-10 = 9)

Sufficient

C

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