Completing the square + Compound Interest

Question 1

What is Compound interest?

Answer 1

Compound interest is interest calculated on the initial principal and also on the accumulated interest of previous periods of a deposit or loan.

Question 2

Sebastian leaves £3000 in the bank for two years.
It earns compound interest of 2% per year.
Calculate the total amount Sebastian has in the bank at the end of the two
years.

Answer 2

£3121.20

Question 3

The value of a television was £600 on 1st March 2013.
Every four months, the value of the television decreased by 8% of its value at
the start of that four months.
What was the value of the television on 1st March 2014?

Answer 3

£467.21

Question 4

A radioactive substance decays over time.
Every year its mass decreases by 14%.
How many years will it take for 500kg of the substance to decay to a mass less
than 200kg?

Answer 4

7 years

Question 5

James weighed 100kg.
His target was to weigh 80kg or less.
His weight decreased by 3% each month.
Has he achieved his target after six months?

Answer 5

No, he hasn’t reached his target after 6 months