math

posted by .

A company is considering implementing one of two quality control plans for monitoring the weights of automobile batteries that it manufactures. If the manifacturing process is working properly, the battery weights are approximatedly normally distributed with a specified mean and standard deviation.

Qaulity control plan A calls for rejecting a battery as defective if its weight falls more than 2 standard deviations below the specified mean.
Qaulity control plan B calls for rejecting a battery as defective if its weight falls more than 1.5 interquartile ranges below the lower quartile of the specified population.

a) What proportions of batteries will be rejected by plan A?
I got .025.

b) What is the probability that at least 1 of 2 randomly chosen batteries will be rejected by plan A?
I am completely drawing blank on this one.

c) What proportions of batteries will be rejected by plan B?
I don't know how to do this one either.

  • math -

    9-1

  • Statistics -

    a) .0225
    b) =1-P(x=0)=.0445
    c) I do not know.

  • statistics -

    c. Q3-Q1=IQR
    -.67-.67=1.34
    Z=Q1-1.5IQR
    Z=.67-1.5(1.34)
    Z=-2.68
    P(Z>-2.68)=.0037

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Statistics

    . A certain company makes 12-volt car batteries. After many years of product testing, the company knows that the average life of a battery is normally distributed, with a mean of 45 months and a standard deviation of 7 months. If the …
  2. statistics

    The numbers of hours of life of a torch battery is normally distributed with a mean of 150 hours and standard deviation of 12 hours. In a quality control test, two batteries are chosen at random from a batch. If both batteries have …
  3. Statistics

    The weights of adult males are normally distributed with a mean of 172 lb and a standard deviation of 29 lb Q.Find the weight that divides the upper 2% of weights from the lower 98%
  4. statistics

    The weights of certain machine components are normally distributed with a mean of 9.75g and a standard deviation of 0.08g. Find the weights that separate the top 5% and the bottom 5%.
  5. statistics

    The actual weights of bags of pet food are normally distributed.The mean of the weights is 50.0lb,with a standard deviation of 0.2lb. Sketch a normal cuve for the distribution.Label the x-axis at one,two,and three standard feciation …
  6. Statistics

    The actual weights of bag of pet food are normally distributed.The mean of the weights is 50.0 lb,with a standard deviation of 0.2 lb. B) In a group of 250 bags,how many would you expect to weigh more than 50.4 lb?
  7. statistics

    The actual weights of bag of pet food are normally distributed.The mean of the weights is 50.0 lb,with a standard deviation of 0.2 lb. C)In a group of 50 bags,how many would yu expect to be within 1.5 standard deviations of the mean?
  8. Math

    The weights of male babies less than 2 months old in the United States is normally distributed with a mean of 11.5 pounds and a standard deviation of 2.7 pounds. How do I find the 80th percentile for these weights?
  9. Sampling Distributions

    A firm produces batteries that have a lifetime which is normally distributed with a mean of 360 minutes and a standard deviation of 30 minutes. The firm needs to keep an eye on the production process to ensure that everything is working …
  10. Data Analysis

    A firm produces batteries that have a lifetime which is normally distributed with a mean of 360 minutes and a standard deviation of 30 minutes. The firm needs to keep an eye on the production process to ensure that everything is working …

More Similar Questions