# math

posted by .

A traffic engineer plans to estimate the average number of cars that pass through an intersection each day. Based on previous studies the standard deviation is believed to be 52 cars. She wants to estimate the mean to within ± 10 cars with 90 percent confidence. The needed sample size for n is:

• math -

eric's note book has 30 pages.he wants to write a number on each page. how many digits will he wite in his note book

• math -

n=8

## Similar Questions

1. ### maths

the police officer also gathered data on the speedsx, in kilometers per hour (km/h) of some cars as they drove down the hill towards her car. the speed limit is 50 km/h. Analysis of the results showed that the speeds of cars were normally …
2. ### stats

The number of cars sold annually by used car salespeople is normally distributed with a standard deviation of 19.22. A random sample of salespeople was taken and the number of cars each sold is listed her. 79 43 58 66 101 63 79 33 …
3. ### AP Calculus AB

A traffic engineer monitors the rate at which cars enter a freeway onramp during rush hour. From her data, she estimates that between 4:30 pm and 5:30 pm, the rate R(t) at which cars enter is given by: R(t)=100(1-0.00012t^2) cars per …
4. ### Ap calc

A traffic engineer monitors the rate at which cars enter a freeway onramp during rush hour. From her data, she estimates that between 4:30pm and 5:30pm the rate R(t) at which cars enter is given by: R(t)= 100(1-0.00012t^2) car per …
5. ### Calculus

Transportation engineers use traffic flow data to design the timing of traffic lights at intersections. At a certain intersection, the traffic flow, F(t), is modeled by the function F(t)=82+4sin(t/2) when 0¡Üt¡Ü30 minutes, where …
6. ### statistics

Consider the average available for all hotel rooms from the previous assignment. Identify the point estimate of the average number of available hotel rooms in this lesson from each sample. Construct and Interpret a 95% confidence level …
7. ### Probability and Statistics

The major would like to estimate the mean number of automobile crashes per day at the intersection of 2 highways. A random sample of 40 days worth of data had a mean of 4.3 crashes and a standard deviation of 0.9. How large of a sample …
8. ### BUSSINESS STATISTICS

Consider the average available for all hotel rooms from the previous assignment. Identify the point estimate of the average number of available hotel rooms in this lesson from each sample. Construct and Interpret a 95% confidence level …
9. ### statistics

The number of cars sold annually by used car salespeople is normally distributed with a standard deviation of 18. A random sample of 310 salespeople was taken and the mean number of cars sold annually was found to be 71. Find the 94% …
10. ### Statistics

Country Insurance wants to estimate the cost of damage to cars due to accidents. The population standard deviation of the cost is assumed at \$200. They want to estimate the mean cost using a 95% confidence interval with a maximum margin …

More Similar Questions