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I have a set of four numbers. 7.5, 18.5, 424 and 0.

Certain percentage is associated with each of it, viz 1.66%, 4.11%, 94.22% and 0.1% resp, which in total is 100%.

I want to know how these percentages were calculated? Can a generic formula be applied ?

Sara
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    Have you tried finding the total, and then calculating various fractions based on the four numbers? – Toby Mak Jun 30 '20 at 10:45
  • @TobyMak I could only guess. But, I need a generic formula to calculate such percentages. I would be getting a lot of such records. Also, I am lost as to how to calculate these percentages. – Sara Jun 30 '20 at 10:53
  • Why do you mean guess? Surely the total is equal to $7.4+18.5+424+0$. Where's the confusing part? – Matti P. Jun 30 '20 at 10:54
  • @MattiP. The confusing part to me is how are these 1.66%, 4.11% calculated? I – Sara Jun 30 '20 at 10:56
  • So the total is $449.9$. A task for you: how many per cent is $7.5$ of $449.9$? How would you calculate it? – Matti P. Jun 30 '20 at 11:01
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    @MattiP. 7.5 / 449.9 * 100 = 1.66%. That was totally fluke for me. I went through pie chart generation and found the formula. But, these calculations are still bouncers for me. And I am already sitting in a corner and crying for not able to understand. – Sara Jun 30 '20 at 11:08
  • @Sara That's correct! The other percentages are calculated similarly. But I suspect that there's some rounding going on. The last number is $0$, and it's supposed to be $0.1~%$ of the total. That cannot be correct. So I suspect that some rounding down has been carried out in the non-percentage numbers. So is there something that is still confusing you? You did manage to calculate the first one yourself. – Matti P. Jun 30 '20 at 11:11
  • @MattiP. may be first one should have been 1.67%? – Sara Jun 30 '20 at 11:13
  • @Sara Good, you are exactly correct! I agree with you, and as we can see, there is indeed something fishy going on with rounding ... I would say: Don't worry about these small details, the point is that you know how to calculate the percentage. In this context, we can say that if you get the result of $1.67~%$, it's the same as $1.66~%$ because some rounding has been applied to the numbers. – Matti P. Jun 30 '20 at 11:15
  • @MattiP. thank yo so much. I am going to imprint this phrase in my mind; 'how many percent is x of total'? – Sara Jun 30 '20 at 11:20
  • Good. So are you now confident that you know how to make these calculations? – Matti P. Jun 30 '20 at 11:20
  • @MattiP. pls write an answer, if possible. will accept that – Sara Jun 30 '20 at 11:22

1 Answers1

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Simply put: The individual percentage is equal to the individual number divided by the total (and multiplied by $100~\%$). The total is simply $$ \text{total} = 7.5 + 18.5 + 424 + 0 = 450 $$ Therefore, the percentages are $$ \frac{7.5}{\text{total}}, \qquad \frac{18.5}{\text{total}}, \qquad \text{etc.} $$ NB: In this case, some rounding has been applied to the numbers, so don't worry about the minor rounding details (unless you really have to!).

Sara
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Matti P.
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