probability and statistics

the average age for licensed drivers in the country is u=40.3 years with a standard deviation of o= 13.2 years.
a. a researcher obtained a random sample of n=16 parking tickets and computed an average age of m=38.9 years for the drivers. is it reasonable to conclude that this set of n=16 people is a representative sample of licensed drivers?
b. the same researcher obtained a random sample of n=36 speeding tickets and computed an average age of m=36.2 years for the drivers. compute the z-score for the sample mean and find the probability of obtaining an average age this young or younger for a random sample of licensed drivers. is it reasonable to conclude that this set of n= 36 people is a representative sample of licensed drivers?

1. 👍
2. 👎
3. 👁
1. Z = (mean1 - mean2)/standard error (SE) of difference between means

SEdiff = √(SEmean1^2 + SEmean2^2)

SEm = SD/√n

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

1. 👍
2. 👎

Similar Questions

1. Math, help asap!

The circle graph shows the distribution by age group of licensed drivers in the US in 2003. If there were approximately 196 million licensed drivers in 2003, which is the closest to the number of drivers in millions who were less

2. fnu

The average age of doctors in a certain hospital is 50.0 years old. Suppose the distribution of ages is normal and has a standard deviation of 4.0 years. If 16 doctors are chosen at random for a committee, find the probability

3. Math

In a recent year there were the following numbers (in thousands) of licensed drivers in the United States. MALE: Age 19 and under - 4746 Age 20 - 1625 Age 21 - 1679 FEMALE: Age 19 and under - 4517 Age 20 - 1553 Age 21 - 1627

4. Statistics

The average age of chemical engineers is 37 years with a standard deviation of 4 years. If an engineering firm employs 25 chemical engineers, find the probability that the average age of the group is greater than 38.2 years old.

1. Stats.

The average age of a vehicle registered in the United States is 8 years, or 96 months. Assume the standard deviation is 16 months. If a random sample of a group of 48 vehicles is selected find the probability that the mean of the

2. statistics

A group of 49 randomly selected construction workers has a mean age of 22.4 years with a standard deviation of 3.8. According to a recent survey, the mean age should be mu=21.9. Test this hypothesis by constructing a 98%

3. arithmetic mean

the average age of 5 children is 8 years. if the age of the father is included , the average increased by 7 years. find the age of the father.

4. stats

The president of a large university wishes to estimate the average age of the students presently enrolled. From past studies, the standard deviation ó is known to be 2 years. A sample of 50 students is selected and the mean is

1. statistics

The average age of a vehicle registered in the U.S. is 8 years, or 96 months. If a random sample of 36 vehicles is selected, find the probability that the mean of their age is between 98 and 100 months. Assume the standard

2. Statistics

the heights of young women are approximately Normal with 65 inches and standard deviation 2.5 inches. The heights of men in the same age group have mean 70 inches standard deviation 2 inches. What percentage of women are taller

3. statistics

2. At a local university, a sample of 49 evening students was selected in order to determine whether the average age of the evening students is significantly different from 21. The average age of the students in the sample was 23

4. Math

Roughly speaking, the standard deviation indicates how far, on average, the observations are from the mean. Do you think that for the data set below the standard deviation will give a good indication of the typical deviation from