Question

After accelerating for 20 seconds, a DeLorean sports car has a wide range of speeds that it can achieve, depending on traction. The distribution of speed follows an approximately normal distribution with a mean of 80 mph and a standard deviation of 7 mph. What percentage of the trials will give the DeLorean a speed between 66 mph and 87 mph?

Answer 1

Answer:

81.859%

Step-by-step explanation:

We solve the question using z score formula

z = (x-μ)/σ, where

x is the raw score

μ is the population mean = 80 mph

σ is the population standard deviation = 7 mph

For x = 66 mph

z = 66 - 80/7

z = -2

Probability value from Z-Table:

P(x = 66) = 0.02275

For x = 87 mph

z = 87 - 80/7

z = 1

Probabilith value from Z-Table:

P(x = 87) = 0.84134

The probability of the trials will give the DeLorean a speed between 66 mph and 87 mph is calculated as:

P(x = 87 mph) - P(x = 66 mph)

0.84134 - 0.02275

= 0.81859

The percentage of the trials will give the DeLorean a speed between 66 mph and 87 mph?

100 × 0.81859

81.859%