Answer:
0.4859
Step-by-step explanation:
The formula for calculating a z-score is is z = (x-μ)/σ,
where x is the raw score,
μ is the population mean, and
σ is the population standard deviation.
From the question:
mean μ = 38,000
standard deviation σ = 7,000
For.
36 ( thousand miles) = 36,000
z = (x-μ)/σ
z = 36,000 - 38,000/7000
z = -0.28571
Probability value from Z-Table:
P(x = 36000) = 0.38755
For 46 thousand miles = 46,000
z = (x-μ)/σ
z = 46,000 - 38,000/7000
z =1.14286
Probability value from Z-Table:
P(x = 46000) = 0.87345
The proportion of tires that have lifetimes between 36 and 46 thousand miles is calculated as:
P(x = 46000) - P(x = 36000)
0.87345 - 0.38755
= 0.4859
