Chi square
A phone battery manufacturer claims that his battery lives are approximately normally distributed with a standard deviation equal to 0.9 years. Suppose a random sample of 10 of these batteries has a standard deviation of 1.2 years. Do you think that the standard deviation is greater than 0.9 years? Use a 0.05 level of significance.
Result
Result

Showing 1 comment:
Dr Math
Answer is NO. These is no reason to doubt, that the standard deviation is 0.9 year
Tips for related online calculators
You need to know the following knowledge to solve this word math problem:
Related math problems and questions:
- A professor
A professor in a typing class found out that the average performance of an expert typist is 85 words per minute. A random sample of 16 students took the typing test, and we obtained an average speed of 62 words per minute with a standard deviation of 8. C
- A random
A random sample of 225 nails in a manufacturing company is gathered. The engineer specified that the specified length of a nail must be 8 cm having a standard deviation of 0.04 cm. It shows from the sample that the average length of the nails is 8.055 cm.
- Confidence interval
A food testing laboratory in Abu Dhabi has been commissioned to estimate the amount of olive oil contained in 1-gallon tins purchased from a range of international olive oil producers. The manufacturers state that the standard deviation of the amount of o
- 68-95-99.7 rule
Assume the resting pulse rates for a sample of individuals are normally distributed with a mean of 70 and a standard deviation of 15. Use the 68-95-99.7 rule to find the following quantities. a. Percentage of pulse rates less than 70 b. Percentage of puls
- Bulb life
Tests show that the lives of light bulbs are normally distributed with a mean of 750 hours and a standard deviation of 75 hours. Find the probability that a randomly selected light bulb will last between 675 and 900 hours.
- Stoaches
Stoaches are fictional creatures distantly related to bigfoot and yeti. Stoach weights are normally distributed, with a mean of 904g and a standard deviation of 104g. State the probability that the sample mean of a random sample of 36 stoach weights excee
- Suppose 6
Suppose the life span of a revolutionary light bulb is normally distributed with a mean life span of 70 thousand hours and a standard deviation of 3 thousand hours. If a light bulb is chosen at random: a) what is the probability the life span will be with