q: Ravi can do a piece of work in 15 days while Prakash can do it in 6 days. In how many days will they finish it together?
Options:
(A) 5 7/9 days
(B) 6 7/9 days
(C) 5 1/9 days
(D) 5 7/2 days
(E) 4 2/7 days
a: Stream of consciousness: 1/15 + 1/6 = 7/30
30/7 = 4 2/7 days The answer is (E).
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q: Ann invested a certain sum of money in a bank that paid simple interest. The amount grew to $240 at the end of 2 years. She waited for another 3 years and got a final amount of $300. What was the principal amount that she invested at the beginning?
Options:
(A) $150
(B) $175
(C) $200
(D) $210
(E) $220
a: Stream of consciousness: Amount at end of 2 years = 240$
Amount at end of 5 years = 300$
Difference in amount for time period of 3 years = 60$
Annual Interest earned = 60/3 = 20$
Principal amount invested at the beginning = 240 - 2*20 = 200$ The answer is (C).
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q: A and B can do a work in 5 days and 10 days respectively. A starts the work and B joins him after 2 days. In how many days can they complete the remaining work?
Options:
(A) 6 days
(B) 2 days
(C) 8 days
(D) 3 days
(E) 9 days
a:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Stream of consciousness: Work done by A in 2 days = 2/5
Remaining work = 3/5
Work done by both A and B in one day = 1/5 + 1/10 = 3/10
Remaining work = 3/5 * 10/3 = 2 days. The answer is (B).
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