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Bone Density Test. In Exercises 1鈥4, assume that scores on a bone mineral density test are normally distributed with a mean of 0 and a standard deviation of 1.

Bone Density For a randomly selected subject, find the probability of a score greater than -2.93.

Short Answer

Expert verified

The probability of a randomly selected score being greater than 鈥2.93 is 0.9983.

Step by step solution

01

Given information

The bone mineral density test scores are normally distributed with mean value of 0 and standard deviation of 1.

02

Describe the random variable

Let Z be the random variable for bone mineral density test scores.

Z~N,2~N0,12

03

Describe the required score

The probability of a randomly selected score being greater than 鈥2.93 is expressed as,

PZ>-2.93

Since the probability has one-to-one correspondence with the area under the curve, the expression infers to the right tailed area of 鈥2.93.

Thus, the area to the right of 鈥2.93 is 1 minus the area to the left of 鈥2.93.

Mathematically,

PZ>-2.93=1-Areatotheleftof-2.93=1-PZ<-2.93...1

04

Obtain the z-score from the standard normal table

Using the standard normal table, the cumulative probability of corresponding to intersection of row 鈥2.9 and column 0.03 is 0.0017.

Thus, PZ<-2.93=0.0017.

Substituting in equation (1),

PZ>-2.93=1-0.0017=0.9983

Therefore, the probability of any randomly selected score being greater than 鈥2.93 is 0.9983.

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