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Question
If x varies inversely as y and x = 20 when y = 600, find y when x = 400.
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Solution
If x varies inversely as y.
∴ xy = k (constant) ...(i)
If x = 20 and y = 600
∴ xy = 20 × 600 = 12000
⇒ k = 12000
When x = 400, then from equation (i),
y × 400 = k
⇒ y × 400 = 12000 ...[Putting the value of k]
⇒ `y = 12000/400 = 30`
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