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Question
l varies directly as m and l is equal to 5, when `m = 2/3`. Find l when `m = 16/3`.
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Solution
If l varies directly as m.
∴ `l/m = k` = (constant)
If l = 5 and m = `2/3`
∴ `l/m = 5/(2/3)`
= `5/1 xx 3/2`
= `15/2`
⇒ `k = 15/2`
When `m = 16/3`, then from equation (i),
`l/(16/3) = 15/2` ...[Putting the value of k]
⇒ `l = 15/2 xx 16/3 = 40`
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