How many proper and improper subsets are there in the set K = { a, b, c, d, e}?

Differentiate Cos25º - Sin 25º

The mean of the numbers 13, 16, x, 18, 21, 2x, 35, is 22. Find the value of x

Find the variance of a group of data whose standard deviation is 12.34 to the nearest whole number.

Calculate the standard deviation of the following scores 5, 4, 6, 7, and 8