Subject: General Aptitude · Chapter: H.C.F. and L.C.M. of Numbers · Exam: 2006 · Marks: · Difficulty:
Four bells begin to toll together and toll respectively at intervals of 6, 7, 8 and 9 seconds. In 1.54 hours, how many times do they toll together and in what interval (seconds)?
(a)14, 504
(b)14, 480
(c)12, 504
(d)16, 580
Answer
Answer (as printed): C
Explanation
Interval after which the bells will toll together $=(\mathrm{L} . \mathrm{C} . \mathrm{M}$. of $6,7,8,9) \mathrm{sec}=504 \mathrm{sec}$. In 1.54 hours, they will toll together $\left[\left(\frac{1.54 \times 60 \times 60}{504}\right)+1\right]$ times $=12$ times.
Explanation as extracted from the printed page; notation may be imperfect.