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MATH HELP PLEASE HELP ASAP?

A pitcher's earned run average (a) varies directly as the number of earned runs (r) allowed and inversely as the number of innings (i) pitched. Jim Jackson had an earned run average of 2.52. He gave up 98 runs in 350 innings. About how many earned runs would he have given up if he had pitched 411 innings with the same average?

If m varies directly as n and inversely as o, and m = 20 when n = 50 and o = 10,

find m when n = 96 and o = 16.

If c varies jointly as f and g, and c = 27 and f = 18 and g = 6, find c when f = 30

and g = 10.

1 Answer

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  • 1 decade ago
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    Earned run average is

    earned runs divided by innings pitched times 9

    or as an equation

    ER/I * 9 = ERA

    plug in what you know

    ER/411 * 9 = 2.52

    ER/411 = 2.52/9

    ER/411 = .28

    ER = .28 *411

    ER = 115.08 (but you can't give up a partial run so we have rounding error)

    So the answer is 115 runs

    n has gone from 50 to 96 and it varies directly so the effect on m would be

    m * 96/50

    with m = 20 this becomes

    20*96/50 = 38.4

    but then it varies inversely with o

    o went from 10 to 16 so that would be expressed as

    m divided by 16/10 which is the same as

    m*10/16

    with m equal to 38.4

    38.4*10/16 = 24

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