Suppose that of a cohort of 150 mice in a mouse colony born in February, 125 are still at the end of March and 115 are still alive at the end of April. What is the survivorship up to the start of April? Round to the nearest hundredth.

Answer: Survival rate up to start of April = 76.67%

Explanation: size of colony = 150mice.

Size of colony in February = 125mice.

Size of colony in march = 115 mice.

1. Survivorship rate in February

= Size of colony / size in February * 100.

= 122 / 150 * 100

= 83.33% to the nearest hundredth

2. Survivorship rate in march

= Size of colony / size in march * 100.

= 115/150 * 100

= 76.67% to the nearest hundredth.