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LostInParadise's avatar

How would you calculate in your head the decimal value of 93/95 rounded to two decimal places?

Asked by LostInParadise (31924points) April 14th, 2016

One thing you could do is to say that 93/95 is greater than 93/100 = .93.

Here is a way of thinking about this that should suggest a way of honing in on the correct value to two places. Imagine that a team has won 93 of its first 95 games, giving it a winning rate of 93/95. 93/100 is what its record would be if it lost its next five games. Intuitively, playing at 0% should have a greater impact on the team’s winning rate than if it played those 5 games at a rate closer to its current winning rate.

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7 Answers

Stinley's avatar

I did long division. Got it a bit wrong as I got to 0.94 but my calculator says 0.98

I don’t get the next bit of your description

CWOTUS's avatar

I would try it in reverse. That is, 93 ÷ 95 is short of a perfect 1 by 2 ÷ 95. And that will be just a bit over 2% (2 ÷ 100), but so close that the problem should round out to 0.98, I think.

LostInParadise's avatar

Yes that works. I was thinking along the lines of a way that you could show that .98 is the correct answer. I will explain what I had in mind later.

Stinley's avatar

I get what @CWOTUS says

I’m a bit of an enthusiastic beginner with maths problems so l think that if I get it, most bright but not mathematically trained people will get it

LostInParadise's avatar

Here is what I had in mind. Suppose the team that won 93 out of 95 games then won their next 5. That would raise their winning rate to 98/100 = .98, so 93/95 is less than .98. Now suppose instead they win 4 of their next 5 games, playing at a rate of .8. This lowers their winning rate to 97/100 = .97. So we know that .97 < 93/95 < .98.

Jak's avatar

Wanting to keep my brain from melting, I wouldn’t.

longgone's avatar

@LostInParadise That’s awesome. Thank you!

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