# Statistics Help Please!: Representing Data & CodingWatch

#1
Hey guys. I just wondered whether you could tell me how to do the following please. My teacher is useless, i can't even remember doing it in class to be honest This isn't homework by the way, just revision so I would appreciate as much help as possible.

Representing Data:

1. How to I work out the mean using a histogram about how long cars were in a repair shop given time on x axis, frequency density on the y axis. It's a sample of 120 cars. Using this I have worked out the frequency of each time but then how to I work out the mean time?

2. There is a cumulative frequency curve for 2 checkouts at a supermarket recording the amount of money spent from a sample of 60 customers. All I am given is the amount spent in classes and a cumulative frequency for checkout A and B. I have to work out the median (3 marks) and interquartile range (4 marks). Do I just draw a line across at the median, LQ and UQ or is it more than this?

How do I then work out the mean amount spent at one of the checkouts, give the amount in classes and the cumulative frequency for each class?

3. Similarly given classes, frequency and frequency density how to I work out the mean?

Coding:

1. On a stem and leaf diagram i have to work out the median and interquartile range. I know how to do the median by just keep crossing ones off of each end but how to I work out the interquartile range?

2. Similarly given two sets of data and I need to find the median, upper quartile and lower quartile of 11 numbers.

3. A student calculates some properties of the volumes of a sample of 8 solid objects. To make it easier he substracts 200cm3 from each volume. The results are sumerised as:

E(x-20)=17000 and E(x-200)^2= 86000000. Find the mean volume. Then calculate the value of E(x-300)

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#2
Anyone?
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