Question

The cost of a diamond varies as the square of its weight. A diamond weighing 20 decigrams costs Rs. 4,800. Find the cost of a diamond of the same kind weighing 8 decigrams.​

Answer 1

Answer:

768

Step-by-step explanation:

let C represent cost and w weight, then the equation relating them is

C = kw² ← k is the constant of variation

To find k use the condition w = 20, C = 4800, that is

4800 = k × 20² = 400k ( divide both sides by 400 )

12 = k

C = 12w² ← equation of variation

When w = 8, then

C = 12 × 8² = 12 × 64 = 768