Question

Four bells ring at intervals of 6, 7, 8 and 9 seconds respectively. All the bells ring together after ............ seconds

• A. 504
• B. 516
• C. 508
• D. 512

Answer 1

Answer: (A)

504

$2|\underset{–}{6,7,8,9}$
$3|\underset{–}{3,7,4,9}$
$|\underset{–}{1,7,4,3}$
$LCM=2\times 3\times 7\times 4\times 3=504$.