List of top Mathematics Questions on Standard deviation

A simple random sample consists of five observations: 4, 5, 9, 10 & 12. What is the point estimate of population standard deviation?

A cab hire firm has two cabs, which it hires out day by day. The number of demands for cabs on each day follows a Poisson distribution with mean of 1.5. The probability of days on which neither cab is used is (Use \( e^{-1.5} = 0.2231 \)):

Which of the following is correct for standard deviation, where \(\bar{X}\) = mean