statistics

posted by .

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 a life less than 120 hours, the batch is rejected. Find the probability that the batch is rejected.

  • statistics -

    Z = (score-mean)/SD = (120-150)/12

    Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to that Z score.

    The probability of both/all events occurring is found by multiplying the individual probabilities.

    I hope this helps.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. statistics

    Section 5.3: Normal Distributions: Finding Values Answer the questions about the specified normal distribution. Q1: The lifetime of ZZZ batteries are normally distributed with a mean of 265 hours and a standard deviation รณ of 10 hours. …
  2. Math

    The lifetime of a SuperTough AAA battery is normally distributed with mean of 28.5 hours and standard deviation of 5.3 hours. For a battery selected at random, what is the probability that the lifetime will be 25 hours or less?
  3. Statistics

    The lifetimes of batteries produced by a firm are known to be normally distributed with a mean of 100 hours and a standard deviation of 10 hours. What is the probability a battery will last between 110 and 120 hours?
  4. statistics

    The life span of the battery pack is known to be Normally distributed with a mean of 250 hours and a standard deviation of 20 hours. How to find the percentage of the battery packs lasting more than 250 hrs.
  5. statistics

    Urgen!! Statistics homework help? Your company is producing special battery packs for the most popular toy during the holiday season. The life span of the battery pack is known to be Normally distributed with a mean of 250 hours and
  6. math

    The lifetime of a SuperTough AAA battery is normally distributed with mean of 28.5 hours and standard deviation of 5.3 hours. For a battery selected at random, what is the probability that the lifetime will be 34 hours or less?
  7. statistics

    A company produces batteries whose lifetimes are normally distributed with a mean of 100 hours. It is known that 90% of the batteries last at least 40 hours. (i). Estimate the standard deviation lifetime. (3 marks) (ii). What percentage …
  8. Statistics

    the average numbers of hours a cat sleep is approximately normally distributed with a mean of 15 hours and a standard deviation of 1.7 hours; what percentage of cats sleep between 13 and 18 hours
  9. Probablity

    The life time of a certain kind of batteries has a mean life of 400 hours and standard deviation as 45 hours. Assuming the distribution of life to be normal, find i) the percentage of batteries with a life time of atleast 470 hours. …
  10. Statistics

    A company makes batteries with an average life span of 300 hours with a standard deviation of 75 hours. Assuming the distribution is approximated by a normal curve fine the probability that the battery will last . Less than 250 hours …

More Similar Questions