Respuesta :
Answer:
1. 0.2422 = 24.22% probability that a hamburger selected at random will weigh between 7.76 and 8.02 ounces
2. 0.1056 = 10.56% probability that a hamburger selected at random with less than 7.52 ounces.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
A sample of 500 hamburgers reveals the average precooked weight to be 8.02 ounces, with a standard deviation of .4 ounce.
This means that [tex]\mu = 8.02, \sigma = 0.4[/tex]
1. What is the probability that a hamburger selected at random will weigh between 7.76 and 8.02 ounces?
This is the pvalue of Z when X = 8.02 subtracted by the pvalue of Z when X = 7.76. So
X = 8.02
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{8.02 - 8.02}{0.4}[/tex]
[tex]Z = 0[/tex]
[tex]Z = 0[/tex] has a pvalue of 0.5
X = 7.76
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{7.76 - 8.02}{0.4}[/tex]
[tex]Z = -0.65[/tex]
[tex]Z = -0.65[/tex] has a pvalue of 0.2578
0.5 - 0.2578 = 0.2422
0.2422 = 24.22% probability that a hamburger selected at random will weigh between 7.76 and 8.02 ounces.
2. What is the probability that a hamburger selected at random with less than 7.52 ounces?
This is the pvalue of Z when X = 7.52. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{7.52 - 8.02}{0.4}[/tex]
[tex]Z = -1.25[/tex]
[tex]Z = -1.25[/tex] has a pvalue of 0.1056
0.1056 = 10.56% probability that a hamburger selected at random with less than 7.52 ounces.
