Question

A marine biologist is testing a new spray, he applies the spray to a sample of $200$ square feet of the beach. $184$ square feet is free of red tide in $7$ days. Under same conditions, if spray has been used for the entire area of $10000$ square feet, then calculate the area free from red tide.

• A. $800$ sq ft
• B. $920$ sq ft
• C. $8,000$ sq ft
• D. $9,200$ sq ft

Answer 1

The correct option is A $800$ sq ft

Given 184 square feet area is free of red tide in $200$ square feet in sample

Then area not free from red tide $=200-184=16$ sq feet

Then entire area free from red tide in $10000$ sq feet $=$ $\frac{16}{200}\times 10000=800$ square feet