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# S2 help watch

1. For question 1)a why do we sub in 5. Can't we sub in 4 or 3 cause it's in the range

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2. (Original post by Lilly1234567890)

For question 1)a why do we sub in 5. Can't we sub in 4 or 3 cause it's in the range

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But what would F(4) or F(3) give you, or how would it help work out what k is?
3. (Original post by Lilly1234567890)

For question 1)a why do we sub in 5. Can't we sub in 4 or 3 cause it's in the range

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It's a CDF. For x = 5, F(x) must be 1 as this is the last x value in the range.
4. (Original post by Lilly1234567890)

For question 1)a why do we sub in 5. Can't we sub in 4 or 3 cause it's in the range

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What does F(x) represent, and therefore how can you use it to find k
5. (Original post by Lilly1234567890)

For question 1)a why do we sub in 5. Can't we sub in 4 or 3 cause it's in the range

Posted from TSR Mobile
you'd miss out a little bit of the area under the pdf curve if you substituted in 4 or 3.
6. (Original post by SeanFM)
But what would F(4) or F(3) give you, or how would it help work out what k is?
oh yeah i wont get the right k value. thanks!
7. (Original post by aymanzayedmannan)
It's a CDF. For x = 5, F(x) must be 1 as this is the last x value in the range.
thanks !
8. (Original post by samb1234)
What does F(x) represent, and therefore how can you use it to find k
got it. thanks !
9. (Original post by Raees_Sharif)
you'd miss out a little bit of the area under the pdf curve if you substituted in 4 or 3.
thanks !

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