7
Q:
A) 15 min 20 sec. | B) 16 min 40 sec. |
C) 13 min 10 sec. | D) 14 min 40 sec. |
Answer: D) 14 min 40 sec.
Explanation:
Explanation:
Part filled in 4 minutes = 4(1/15 + 1/20) = 7/15
Remaining part = 1 - 7/15 = 8/15
Part filled by B in 1 minute = 1/20
1/20 : 8/15 :: 1 : k
k = (8/15 )x 1 x 20 = 10( 2/3) min = 10 min 40 sec.
The tank will be full in (4 min. + 10 min. 40 sec) = 14 min 40 sec.