The Student Room Group

c12 2015 jan q5

part b)
i found the values from 1-100 which are 14 numbers divisible by seven then multipied the answer by 5 to find n and use in the equation.. i got 70 but the n in the markscheme was 71, why is it wrong 😢
Reply 1
Original post by pondsteps
part b)
i found the values from 1-100 which are 14 numbers divisible by seven then multipied the answer by 5 to find n and use in the equation.. i got 70 but the n in the markscheme was 71, why is it wrong 😢


You're missing a number somewhere but I can't quite tell what's wrong with your approach. The way to do it is to note that 497 is divisible by 7 so there are 497/7 = 71 multiples of 7 between 1 and 500.
Original post by Zacken
You're missing a number somewhere but I can't quite tell what's wrong with your approach. The way to do it is to note that 497 is divisible by 7 so there are 497/7 = 71 multiples of 7 between 1 and 500.


ohhh alright..
but if u do it using my way is zero considered as a multiple?? cos no numbers are missing :/
Reply 3
Original post by pondsteps
ohhh alright..
but if u do it using my way is zero considered as a multiple?? cos no numbers are missing :/


Nopes, 0 doesn't count because it says between 1 and 500. I can see the fault with your method though, the latest multiple of 7 in your list from 1-100 is 98 but 98 * 5= 490, so you're missing the 497 term.
Original post by Zacken
Nopes, 0 doesn't count because it says between 1 and 500. I can see the fault with your method though, the latest multiple of 7 in your list from 1-100 is 98 but 98 * 5= 490, so you're missing the 497 term.


ohh okayyy.. thanks a lot
Reply 5
Original post by pondsteps
ohh okayyy.. thanks a lot


No worries.

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