At a telephone exchange, three phones ring at intervals of 20 sec, 24 sec and 30 seconds. If they ring together at 11 : 25 a.m, when will they next ring together?
Shrenik switched on a bulb at 2 : 39 : 40 hours and switched it off on the same day at 12 : 30 : 34 hours. For how long was the bulb in switched-on mode?
Present age of Amit is twice of Baman’s present age. After 5 years Baman’s age will be 4 times of the Chetan’s present age. If Chetan celebrated his sixth birthday 7 years ago, then what will be the present age (in years) of Amit?
The mean of marks secured by 30 students in division-A of class X is 67, 55 students of division-B is 63 and that of 40 students of division-C is 61. What is the mean of marks of the students of three divisions of Class X?