A is 30% more efficient than B. How much time will they, working together, take to complete a job which A along could have done in 23 days?
Correct answer: B
Explanation
Ratio of times taken by A and B = 100 : 130 = 10 : 13.
Suppose B takes x days to do the work.
Then, 10 : 13 : : 23 : x ⇒ x = (23×13)/10 ⇒ x = 299⁄10
A’s 1 day’s work = 1⁄23; B’s 1 days work = 10⁄299
(A + B)’s 1 day’s work = (1⁄23 + 10⁄299) = 23⁄299 = 1⁄13
∴ A and B together can complete the job in 13 days.
Answer B
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AQuA-RAT items are crowdsourced algebra problems, not ACT questions. They carry five answer choices in the pre-2025 ACT Mathematics style and no ACT reporting category. Useful for drilling Preparing for Higher Math content; not a substitute for a real form.