Mathematics 9709 · AS & A Level · Sampling and estimation

Sampling and estimation — practice question

In Marumbo, three quarters of the adult population own a cell phone.
(i)[3]

A random sample of $8$ adults is selected from Marumbo. Find the probability that the number of adults who own a cell phone lies between $4$ and $6$ inclusive.

(ii)[5]

A random sample of $160$ adults is selected from Marumbo. Use an approximation to find the probability that more than $114$ of them own a cell phone.

(iii)[1]

Justify why the approximation is appropriate in part (ii).

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct binomial probability setup using $p=0.75$

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