PreCalculus
The table below shows a frequency distribution of the number of pickup trucks sold at 85 truck dealerships in Maine over an 18month period.
Number of trucks sold/Number of dealerships:
7090/2
90110/11
110130/39
130150/17
150170/9
170190/7
Find the interval about the sample mean such that the probability is 0.90 that the true mean lies within the interval. (When P=90%, t=1.65)
I know that N=85, but I do not know how to find the standard deviation or mean in order to work the rest of the problem. Any help would be great.

Frankly, I would assign numbers to do the mean, standard deviation.
Change your frequency to actual data
80,80, 100,100,100,100,100,100, (eleven 100's), 120 (39 of these). Your calculator can be your best friend doing this.posted by bobpursley
Respond to this Question
Similar Questions

PreCalculus
The table below shows a frequency distribution of the number of pickup trucks sold at 85 truck dealerships in Maine over an 18month period. Number of trucks sold/Number of dealerships: 7090/2 90110/11 110130/39 130150/17 
math
In one month a salesman sold a total of 30 cars and trucks. If three times the number of cars sold equals twice the number of trucks sold, how many trucks did he sell? 
Math
Sales made last year by Lane's Appliance Store are listed below. The first number tells how many employees made the sales amount. Two sales employees earned in the range of $130,001$150,000. Six sales employees earned in the 
math help
The number of trucks registered in a city increases by 10% each year. Initially, there were 100 trucks registered. There were 110 trucks registered at the end of Year 1. What is the number of trucks registered in the city at the 
Algebra 2
"At a school sponsored car wash, the fees charged were: $5 per car, $8 per truck, $10 per van. Twice as many cars were washed as pickup trucks. The amount collected for washing cars and pickup trucks was $360. A total of $410 was 
econ
Consider the market for trucks. Assume that the demand for trucks is given by 60 2 5 D Q P Y where P is price per truck and Y is the income of the buyers. The supply of trucks is given by 30 5 3 S Q P W where W is the price of all 
Life Management
The Lemon Law pertains to: a. new cars and trucks*** b. used cars and trucks c. only vehicles purchased from the dealerships 
math
i need help with roman numerals asap I is 1 V is 5 X is ten L is 50 C is 100 D is 500 M is 1000 with this you can make any number you can only put 3 of anything in a row though so you can only do III not IIII for 4 you IV if a 
Math
Below are the amounts of money a waiter earned each day last week. $120 , $170 , $150 , $190 , $130 , $200 , $160 . What is the interquartile ? 
PreCalculus
A car manufacturing company (the Company) can produce a car for $3000.00 and a truck for $5000.00. Suppose "C" cars and "T" trucks are sold to the dealer at markups, respectively, of 20 and 30 percent. If the Company made a