MEDIUM
AS and A Level
IMPORTANT
Earn 100

A biased coin is tossed 160 times. The number of heads obtained, H, follows a binomial distribution where EH=100. Find the value of p and the variance of H.

Important Questions on The Normal Distribution

MEDIUM
AS and A Level
IMPORTANT
A biased coin is tossed 160 times. The number of heads obtained, H, follows a binomial distribution where EH=100. Find the approximate probability of obtaining more than 110 heads.
MEDIUM
AS and A Level
IMPORTANT
One card is selected at random from each of 40 packs. Each pack contains 52 cards and includes 13 clubs. Let C be the number of clubs selected from the 40 packs. Show that the variance of C is 7.5.
HARD
AS and A Level
IMPORTANT

One card is selected at random from each of 40 packs. Each pack contains 52 cards and includes 13 clubs. Let C be the number of clubs selected from the 40 packs.

Obtain an approximation for the value of PC8, and justify the use of this approximation.

EASY
AS and A Level
IMPORTANT
In a large survey, 55% of the people questioned are in full-time employment. In a random sample of 80 of these people, find the expected number in full-time employment.
MEDIUM
AS and A Level
IMPORTANT
In a large survey, 55% of the people questioned are in full-time employment. In a random sample of 80 of these people, find the standard deviation of the number in full-time employment.
HARD
AS and A Level
IMPORTANT
In a large survey, 55% of the people questioned are in full-time employment. In a random sample of 80 of these people, find the approximate probability that fewer than half of the sample are in full-time employment.
MEDIUM
AS and A Level
IMPORTANT
A company manufactures rubber and plastic washers in the ratio 4:1. The washers are randomly packed into boxes of 25.
Find the probability that a randomly selected box contains exactly 21 rubber washers.
MEDIUM
AS and A Level
IMPORTANT
A company manufactures rubber and plastic washers in the ratio 4:1. The washers are randomly packed into boxes of 25.
Find the probability that a randomly selected box contains exactly 10 plastic washers.