If a man walks to his office at 3/4 of his usual rate, he reaches office 1/3 of an hour later than usual. What is his usual time to reach office.  Choose the correct choice from the following choices:
A) 1⁄2 hr	B) 1 hr	C) 3⁄4 hr	D) 2 hrs	E) None of these
If new speed is a⁄b of original speed, then usual time × (b⁄a - 1) = change in time   ∴ usual time × (4⁄3 - 1) = 1⁄3   ⇒ usual time = 1⁄3 × 3 = 1 hr   Answer 1 hr
<result>B</result>
If a man walks to his office at 3/4 of his usual rate, he reaches office 1/3 of an hour later than usual. What is his usual time to reach office.