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Mis directly proportional to r?

When r= 2, M= 14
a) Work out the value of M when r= 12.
b) Work out the value of r when M = 224.

User Idunnololz
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2 Answers

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User Anton Valqk
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Answer:

M = 84 , r = 32

Explanation:

Given M is directly proportional to r then the equation relating them is

M = kr ← k is the constant of proportion

To find k use the condition when r = 2, M = 14 , then

14 = 2k ( divide both sides by 2 )

7 = k

M = 7r ← equation of proportion

(a)

When r = 12

M = 7 × 12 = 84

(b)

When M = 224 , then

224 = 7r ( divide both sides by 7 )

32 = r

User Aysonje
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