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# S1 question? Help needed.. Watch

1. Could someone provide me with clear explanation of how to complete this question.

Many thanks.
2. (Original post by greentron6)

Could someone provide me with clear explanation of how to complete this question.

Many thanks.
What have you done/ tried to do?

The first step with histogram / interval data is to convert the endpoints to true values.

The next thing you need to do for this question is to work out the total number of people >24.5 and the total sample size.
3. Do what the guy said above then just multiply the probability value you get
Do what the guy said above then just multiply the probability value you get
Im still confused. Could you actually do the question for me, so I can understand better...
5. (Original post by lerjj)
What have you done/ tried to do?

The first step with histogram / interval data is to convert the endpoints to true values.

The next thing you need to do for this question is to work out the total number of people >24.5 and the total sample size.
Im still confused. Could you actually do the question for me, so I can understand better...
6. (Original post by greentron6)
Im still confused. Could you actually do the question for me, so I can understand better...

(Because it asks for over 24.5, that's just the last two entries. If it asked for e.g. 24.3 you'd need to interpolate a little instead of just adding up the numbers in the last two boxes)

Edit: Misread the question - it says that there are two phone calls. That means that this is a "drawing without replacement" style question. The probability that the first call is >24.5minutes is still 11/55, but the second call now has a probability of 10/54 since you presumably made sure it wasn't the same call. So the combined probability is 1/27.
7. This is new to me. Is this still on the spec?
8. (Original post by lerjj)

(Because it asks for over 24.5, that's just the last two entries. If it asked for e.g. 24.3 you'd need to interpolate a little instead of just adding up the numbers in the last two boxes)
How did you get that answer? I did it with the z = X - Mean / Standard deviation
and the used the probability table to get the answer. Which is 0.56155
9. (Original post by greentron6)
This is new to me. Is this still on the spec?
Yes, it's a simple probability question.

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