MEDIUM
AS and A Level
IMPORTANT
Earn 100

When a certain driver parks their car in the evenings, they are equally likely to remember or to forget to switch off the headlights. Find the probability that on the next 16 occasions that they park their car in the evening, they forget to switch off the headlights: 14 more times than they remember to switch them off

Important Questions on The Binomial and Geometric Distributions

MEDIUM
AS and A Level
IMPORTANT
When a certain driver parks their car in the evenings, they are equally likely to remember or to forget to switch off the headlights. Find the probability that on the next 16 occasions that they park their car in the evening, they forget to switch off the headlights: at least 12 more times than they remember to switch them off.
MEDIUM
AS and A Level
IMPORTANT
Gina has been observing students at a university. Her data indicate that 60%of the males and 70% of the females are wearing earphones at any given time. She decides to interview randomly selected students and to interview males and females alternately. Use Gina's observation data to find the probability that the first person not wearing earphones is the third male interviewed, given that she first interviews: a male 
MEDIUM
AS and A Level
IMPORTANT
Gina has been observing students at a university. Her data indicate that 60%of the males and 70% of the females are wearing earphones at any given time. She decides to interview randomly selected students and to interview males and females alternately. Use Gina's observation data to find the probability that the first person not wearing earphones is the third male interviewed, given that she first interviews: a female and state any assumptions made about the wearing of earphones in your calculations
MEDIUM
AS and A Level
IMPORTANT
Gina has been observing students at a university. Her data indicate that 60%of the males and 70% of the females are wearing earphones at any given time. She decides to interview randomly selected students and to interview males and females alternately. Use Gina's observation data to find the probability that the first person not wearing earphones is the third male interviewed, given that she first interviews: a male who is wearing earphones. and state any assumptions made about the wearing of earphones in your calculations
MEDIUM
AS and A Level
IMPORTANT
In Restaurant Bijoux 13% of customers rated the food as 'poor', 22% of customers rated the food as 'satisfactory' and 65% rated it as 'good'. A random sample of 12 customers who went for a meal at Restaurant Bijoux was taken. Find the probability that more than 2 and fewer than 12 of them rated the food as 'good'.
MEDIUM
AS and A Level
IMPORTANT
In Restaurant Bijoux 13% of customers rated the food as 'poor', 22% of customers rated the food as 'satisfactory' and 65% rated it as 'good'. On a separate occasion, a random sample of n customers who went for a meal at the restaurant was taken. Find the smallest value of n for which the probability that at least 1 person will rate the food as 'poor' is greater than 0.95.
MEDIUM
AS and A Level
IMPORTANT
A biased coin is four times as likely to land heads up compared with tails up. The coin is tossed k times so that the probability that it lands tails up on at least one occasion is greater than 99%. Find the least possible value of k.
MEDIUM
AS and A Level
IMPORTANT
Given that X~Bn,0.4 and that PX=1=k×PX=n-1, express the constant k in terms of n, and find the smallest value of n for which k>25.