Two bells ring together. If the bells ring at every 3 minutes and 4 minutes respectively. After what interval of time will they ring together again ?

The three bells ring at 12’O clock every day. The 1st bell rings for every 15 min, 2nd bell rings for every 25 min, 3rd bell rings for every 40 min. At what time will all the bells ring again?

Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 35 minutes respectively. The ratio of the thermal conductivities of their materials is

Two radioactive elements X and Y have half life periods of 50 minutes and 100 minutes respectively. Initially both of them contain equal number of atoms. Find the ratio of atoms left N_(x) //N_(y) after 200 minutes.

A blacksmith fixes Iron ring on the rim of the wooden wheel of a horse cart. The diameter of the rim and the fron ring are 5.243 m " and " 5.231 m, respectively at 27 ^(@)C . To what temperature should the ring be heated so as to fit the rim of the wheel?

Take a clock and fix its minutes hand at 12. Note the angles made by minutes hand in the given intervals of time : Is the angle turned through by the minute hand directly proportional to the time that has passed? Yes! From the above table, you can also see T_(1), T_(2) = A_(1) : A_(2) , becausee T_(1): T_(2) = 15: 30 =1:2 A_(1): A_(2) = 90: 180 =1:2 Check if T_(2): T_(3) = A_(2) : A_(3) and T_(3): T_(4) = A_(3): A_(4) You can repeat this activity by choosing your own time interval.

A sample contains two radioactive substances A and B in the ratio of 4 : 1 . If their half lives are 24 and 16 hours respectively , then after two days what will be the ratio of A and B?

Prasad and Raju met in the market on 1st of this month. Prasad goes to the market every 3rd day and Raju goes every 4th day. On what day of the month will they meet again?

Let A and B be two sets containing 2 elements and 4 elements respectively the number of subsets of A xx B having 3 or more elements is