statistics

The lengths of pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days. Out of 50 pregnancies, how many would you expect to last less than 250 days?

  1. 👍 0
  2. 👎 0
  3. 👁 227
asked by Terry
  1. Assume that the heights of women are normally distributed with a mean of 63.9 inches and a standard deviation of 2.5 inches. The U.S. Army requires that the heights of women be between 58 and 80 inches. If 200 women want to enlist in the U.S. Army, how many would you expect to meet the height requirements?

    1. 👍 0
    2. 👎 0
    posted by Terry
  2. Use z-scores. For your first problem, determine z using the formula:

    z = (x - mean)/sd
    ...where x = 250, mean = 268, and sd = 15.

    Once you have z, check the z-table for the probability (remember the first problem is asking less than 250, so keep that in mind when checking the table). Once you have the probability, multiply 50 by that value you find to get the number you need.

    The second problem is similar to the first, with the exception of finding two z-scores instead of one.
    Find z using 58 for x and also find z using 80 for x. Then use the z-table to find the probability between the two z-scores. Once you have the probability, multiply 200 by that value you find to get the number you need.

    I hope this will help get you started.

    1. 👍 0
    2. 👎 0
    posted by MathGuru

Respond to this Question

First Name

Your Response

Similar Questions

  1. Stat

    The lengths of pregnancies in a small rural village are Normally distributed with a mean of 268 days and a standard deviation of 12 days. What percentage of pregnancies last beyond 290 days?

    asked by Vlad on February 13, 2017
  2. Statistics

    The lengths of pregnancies are normally distributed with a mean of 273 days and a standard deviation of 20 days. If 64 women are randomly selected, find the probability that they have a mean pregnancy between 273 days and 275

    asked by Jane on February 10, 2013
  3. Statistics

    Males make a mean of 531 on math SAT with standard deviation of 114. Minimum 600 score. what's the % of males that don't satisfy this requirement? Pregnancies usually distributed mean of 268 days and standard distribution 15 days.

    asked by Sue on December 5, 2006
  4. statistics

    1. When designing motorcycle helmets, the breadth of a person's head must be considered. Men have head breadths that are normally distributed with a mean of 6.0 inches and a standard deviation of 1.0 inches. If one male is

    asked by maczindahouse on February 27, 2019
  5. Math

    Actual lengths of pregnancy terms are nearly normally distributed about a mean pregnancy length (of about 38-39 weeks) with a standard deviation of 15 days: about what percentage of births would be expected to occur within 15 days

    asked by Daniel on February 12, 2013
  6. math,help

    how would i do about this problem can someone explain it to me or show me because i keep getting weird answers with an e at the end. It makes no sence. This question is: The length of human pregnancies from conception to birth

    asked by jasmine20 on February 11, 2007
  7. MAT 201

    The number of vacation days taken by employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. For the next employee, what is the probability that the number of days of vacation

    asked by bob on May 15, 2014
  8. statistics

    The number of vacation days taken by employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. For the next employee, what is the probability that the number of days of vacation

    asked by bob on May 15, 2014
  9. statistics

    The number of vacation days taken by employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. For the next employee, what is the probability that the number of days of vacation

    asked by Jeff on August 17, 2014
  10. Statistics

    An automatic machine in a manufacturing process is operating properly if the lengths of an important subcomponent are independently and normally distributed with a mean of 120 cm and a standard deviation of 4.7 cm. Find the

    asked by Meghan on September 21, 2011

More Similar Questions