A moving boat is observed from the top of a cliff of 150 m height. The angle of depression of the boat changes from 60° to 45° in 2 minutes. What is the speed of the boat in metres per hour ?

A fair coin is tossed four times. What is the probability that at most three…

Two students X and Y appeared in an examination. The probability that X will qualify…

The variance of 20 observations is 5. If each observation is multiplied by 2, then…

What is the mean deviation about the mean for the data 4, 7, 8, 9,…

If x̄ and ȳ are the means of two distributions such that x̄ < ȳ…