SSC CGL Official PYQQuantitative Aptitude12 Sep 2025 (Shift 1)
Q.
Three pumps, A, B, and C are capable of filling a reservoir. A fills in 5 hours, B in 7 hours, and C in 10 hours. When all three pumps are opened together, they operate for 1.5 hours before pump C is closed. How much additional time will it take to completely fill the reservoir after that?
A
a) 1/2 hours
B
b) 43/25 hours
C
c) 47/48 hours
D
d) 45/41 hours
Correct Answer: Option C)
Detailed Step-by-Step Explanation:
Rates: A=1/5, B=1/7, C=1/10. Together = 1/5+1/7+1/10 = (14+10+7)/70 = 31/70. In 1.5 hours = (31/70)*1.5 = 46.5/70 = 93/140. Remaining = 47/140. A+B filling rate = 1/5+1/7 = 12/35. Additional time = (47/140) / (12/35) = (47/140) * (35/12) = 47/48 hours.