The following are the last 10 run scores Colin got in cricket:
21, 30, 10, 4, 19, 31, 5, 7, 17, 4
a) Work out Colin's mean score.
b) Colin plays cricket again on Sunday. He gets 17 runs.
What is his new mean score?
Give your answers as decimals.

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?

Which graph of a hyperbola represents the equation 16x^2-y^2=16

Ameteorologist is studying the monthly rainfall in a section of the brazilian rainforest. she recorded the monthly rainfall, in inches, for last year. they were: 10.4, 10.3, 11.7, 11.1, 8.0, 4.4, 2.6, 1.8, 2.5, 4.4, 7.3, 9.5 fill in the missing values in the formula. what is the variance?