Point estimate for the difference between two population proportions is the difference between the two sample proportions, written as:

and the standard deviation is given by

When np and n(1-p) is greater than 5, then the sampling distribution is approximately normal and we can use standard normal methods.
Thus, the propability of a test <span>for the difference between two population proportions is given by

</span>
The number of standard deviations from the mean for a man 72 inches tall is
Z = (72 -69.3)/2.8 ≈ 0.964
83.800 ÷ 1.479 = 56.65 ≈ 56.7 litres of diesel Steve buyed ;
29.99 + 16.99 = 46.98
46.98 + 0.08(46.98) = 46.98 + 3.76 = 50.74 <==