In a classroom the average height of all the boys was 170 cm. Rahim recently joined the class which originally had 20 boys increased the average to 171cm. Then find the height of Rahim.

The average age of a group of 12 students is 20years. If 4 more students join the group, the average age increases by 1 year. The average age of the new students is

The price of a jewel, after passing through three merchants rises on the whole by 80%. If the first and the second merchants earned 20% and 25% profit respectively, find the percentage profit earned by the third merchant.

A constructor estimates that 3 people can paint Mr. khans house in 4 days. If he uses 4 people instead of 3, how long will they take to complete the job?

How many 4-letter words with or without meaning, can be formed out of the letters of the word, LOGARITHMS, if repetition of letters is not allowed?

If 6th March, 2005 is Monday, what was the day of the week on 6th March, 2004?

At 6o clock, a clock ticks 6 times. The time between first and last ticks is 30 seconds. How long does it tick at 12o clock?

Two urns contain respectively 2 red 3 white and 3 red,5 white balls. One ball is drawn at random from the first urn and transferred into the second. A ball is now drawn from the second urn and it turns out to be red. What is the probability that the transferred ball was white?

Two trains A and B start simultaneously from stations X and Y towards each other respectively. After meeting at apoint between X and Y, train A reaches station Y in 9 hours and train B reaches station X in 4 hours from thetime they have met each other. If the speed of train A is 36 km/hr., what is the speed of train B?

An alloy of zinc and copper contains the metals in the ratio 5: 3. The quantity of zinc to be added to 6 kg of the alloy so that the ratio of the metal may be 3: 1 is: