Question

1. If the weekly cost of groceries increases annually at 5%, then the weekly cost, C, of $100 of groceries x years from now will be given by the function C=100(1.05)^x. In how many years will $100 worth of groceries cost $300? Give your answer to the nearest year.

2. 525 g of salt is placed in a jar of water. After 1 minute, 115 g of salt remains undissolved. How long will it take until only 20 g of salt is undissolved? Assume the salt decays exponentially. Give your answer to the nearest unit.

Answer 1

Hence 23 years is the answer.

P = 525, A = 115, at x = 1

Hence it will take 2.15 minutes or approx 2 minutes until only 20 g of salt is undissolved.

2 minutes is the answer as they asking for nearest unit.

Please comment if any doubt. thank you.