Hannah plans to build 3 tennis courts in a local park she will build a fence around the whole area how much fencing will Hannah need each court is the same size

0.0359

Step-by-step explanation:

Data provided:

mean values of three independent times are 15, 30, and 20 minutes

the standard deviations are 2, 1, and 1.6 minutes

Now,

New Mean = 15 + 30 + 25 = 65

Variance = ( standard deviation )²

or

Variance = 2² + 1² + 1.6² = 7.56

therefore,

Standard deviation = √variance

or

Standard deviation =  2.75

Thus,

Z-value =

or

Z-value = - 1.81

from the Z-table

the Probability of Z ≤ -1.81 = 0.0359