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1. 1) peice of data from 9 people. data mean was 35.5 but one of the 9 people gave a value of 42 instead of 32

a) write down effect - obv the mean will increase since 42 is > mean

b) calculate new mean

so i thought b) was 32x8 + 42 divide by 9 but its not. confused!
2. (Original post by seconda1)
1) peice of data from 9 people. data mean was 35.5 but one of the 9 people gave a value of 42 instead of 32

a) write down effect - obv the mean will increase since 42 is > mean

b) calculate new mean

so i thought b) was 32x8 + 42 divide by 9 but its not. confused!
We have where is the total data from 8 people and the 42 is the leftover data from the ninth person who got it wrong.

You want to use this equation to determine the value of
3. (Original post by RDKGames)
We have where is the total data from 8 people and the 42 is the leftover data from the ninth person who got it wrong.

You want to use this equation to determine the value of
im confused was is t?
4. (Original post by seconda1)
im confused was is t?
I've just explained it. It's a variable to denote the total of the other 8 people.

Like y'know, when calculating the mean of like 4 people you'd do something like but you can freely take the sum of the first three numbers 1+2+3 = 6 and just rewrite the mean as . Same idea here, except we do not know the mean of the 8 people so we just denote it by
5. (Original post by RDKGames)
I've just explained it. It's a variable to denote the total of the other 8 people.

Like y'know, when calculating the mean of like 4 people you'd do something like but you can freely take the sum of the first three numbers 1+2+3 = 6 and just rewrite the mean as . Same idea here, except we do not know the mean of the 8 people so we just denote it by
still confused

the mark scheme says 9x35.5 -10 / 9
why is it -10?
6. (Original post by seconda1)
still confused

the mark scheme says 9x35.5 -10 / 9
why is it -10?
Because if you take the eq. I said and proceed to say

then just subtract 10/9 from both sides to get the answer they're looking for.
7. (Original post by RDKGames)
Because if you take the eq. I said and proceed to say

then just subtract 10/9 from both sides to get the answer they're looking for.

so the data was said to have found a mean of 35.5 and then it says one person out of the 9 had the 42 instead of 32 so cant you work out the mean of 8 people because its 32x8/8?

cant seem to get my head around this
8. (Original post by seconda1)

so the data was said to have found a mean of 35.5 and then it says one person out of the 9 had the 42 instead of 32 so cant you work out the mean of 8 people because its 32x8/8?

cant seem to get my head around this
Why would you want the mean of 8 people? Also no, the mean of the 8 people is given by instead.

Anyway, I don't know how else to explain it so I'll leave it to someone else. All I can do is repeat myself by saying that each person has data values of initially. We don't know the values of the first 8 people so we just denote them by 's. Then the mean is given by however we know that the 42 was incorrectly entered instead of 32 therefore we must find the value of instead. I simply denoted the sum since we don't need to do anything with it and it takes up too much space.

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