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If x is inversely proportional to y, and y = 6 when x = 7, find the value of x, when y = 64.
3221тАЛ
3523тАЛ
3322тАЛ
3321тАЛ
3221тАЛ
Use the product constancy rule for inverse proportion: x1тАЛy1тАЛ=x2тАЛy2тАЛ. Here, (7├Ч6)=(x├Ч64).
x is inversely proportional to y. y = 6 when x = 7. Find x when y = 64.
x├Чy=k
Use the product constancy rule for inverse proportion: x1тАЛy1тАЛ=x2тАЛy2тАЛ. Here, (7├Ч6)=(x├Ч64).
Students often treat this as a direct proportion (x/y=k) instead of an inverse proportion (x├Чy=k), leading to the wrong result.
Define the relationship
Since x is inversely proportional to y, their product is a constant k, expressed as x├Чy=k.
x├Чy=k
Calculate the constant k
Using the given values x=7 and y=6, we find the constant k=7├Ч6=42.
k=7├Ч6=42
Solve for x
Now set the product to 42 for y=64: x├Ч64=42. Solving for x gives x=42/64.
x=6442тАЛ
Simplify the fraction
Simplify the fraction by dividing both numerator and denominator by 2: x=21/32.
x=3221тАЛ
A is correct because the constant product is 42, and dividing 42 by 64 results in 21/32.
Inverse proportionality is the foundation for solving 'Work and Time' problems where number of workers is inversely proportional to time taken.