Mathematics 9709 · AS & A Level · The normal distribution

The normal distribution — practice question

For male leopards in one particular region, the weights are normally distributed, with mean $55\text{ kg}$ and standard deviation $6\text{ kg}$.
(a)[4]

Determine the probability that a male leopard chosen at random from this region has a weight between $46\text{ kg}$ and $62\text{ kg}$.

(b)[3]

Female leopard weights in this region are normally distributed with mean $42\text{ kg}$ and standard deviation $\sigma\text{ kg}$. It is known that $25\%$ of female leopards in the region weigh less than $36\text{ kg}$. Find the value of $\sigma$.

(c)[4]

The weight distributions for male and female leopards are independent of one another. A male leopard and a female leopard are each selected at random. Find the probability that both of these leopards weigh less than $46\text{ kg}$.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correctly standardise $46$ and $62$ to $z$-values

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI