Question

The cost of diamond varies as the square of its weight. A diamond welghing 10 decigrams costs R1600. Find the cost of diamond of the same kind weighing 7 decigrams.​

Answer 1

Answer:

Let C be the cost of the diamond and W be its weight.

Given:Cost of a diamond varies as the square of its weight.

⇒C∝W2

⇒C=kW2 where k is the proportionality constant.

Given:A diamond weighing 20 decigrams costs  Rs.4,800

⇒4800=k×202

⇒4800=400k

⇒12=k

⇒k=12

Now,C=12×82

⇒C=12×64=768

∴ cost of a diamond of the same kind weighing 8 decigrams is  Rs.768

Answer 2

Answer:

Cost of the 7 decigrams Diamond = Rs 1120

Step-by-step explanation:

Given that ;

Cost of 10 decigrams Diamond = Rs 1600

Cost of 7 decigrams Diamond = ?

Cost of 1 decigram Diamond = 1600 / 10

= Rs 160

Cost of 7 decigrams Diamond = 160 × 7

= Rs 1120