All problems on growth & decay - full name 'exponential growth & decay' use the formula below, where the time variable 'n' is in the index.

Example #1 - £5000 is invested in a savings bond, which pays 7% p.a.

How much will the bond be worth after 5 years?

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Example #2 - The level of activity of a radio-active source decreases by 5% per hour. If the activity is 1500 counts per second, what will it be 12 hours later?

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Example #3 - A bee-hive increases its population of bees by 8% per year.

How many bees will there be in the hive in 5 years time?

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