Question Part
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The number of ships to arrive at a harbor on any given day is a random variable represented by x. The probability distribution of x is as follows. (Give your answers correct to two decimal places.)
x 10 11 12 13 14
P(x) 0.35 0.15 0.15 0.07 0.28
Formula for the mean:
SUM [x * P(x)]
Take x times P(x) for each value listed. Then add for the mean.
Formula for the variance:
{SUM [x^2 * P(x)] - mean^2}
Square each x. Then take x^2 times P(x) for each value. Add up the values for a total, then subtract mean squared from that total.
For standard deviation:
Take the square root of the variance.