Answer:
Probability = 0.8444
Step-by-step explanation:
To solve this problem, we need to obtain the z-value which corresponds to the probability that the mean of a sample of 84 computers would differ from the population mean by less than 1.39 months
Let x' denote the mean life of the computer.
Mean = 88 months
Variance = 81
Thus, standard deviation = √81 = 9
Thus, we obtain;
P(|x - μ| < 1.39) = P(-1.39 > x < 1.39)
For x' = - 1.39,
z = -1.39/(9/√84)
z = -1.39/0.982
z = -1.42
For x' = 1.39,
z = 1.39/(9/√84)
z = 1.39/0.982
z = 1.42
Thus, P(|x - μ| < 1.39) =
P(−1.42 < z < 1.42)
From the Z-distribution tables i attached, we obtain ;
0.92220 - 0.07780 = 0.8444
22.50 as a fraction is 45/2. Happy to help. :)
B) 12 miles and 12 gallons. The answer is B because gallons and miles are 2 completely different types of measurement. If you look at A, C, D, they all have the same measurements. I hope this helped!