Answer:
The answer to the question is;
The number of papers expected to be handed in before receiving each possible grade at least once is 14.93.
Step-by-step explanation:
To solve the question , we note that it is a geometric distribution question which have equal probabilities and therefore is a form of Binomial distribution with Bernoulli trials, where we are conducting the trials till we have r successes
Since we have r = 6, we will have to find the expected value of the number of trials till the nth paper handed in receives a previously awarded grade.
We therefore have,
The Probability that out of six papers turned 5 are different scores is given by
P(Y=5) = p'= q⁵p = (1-p)⁵p = 3125/46656
Therefore p' = the probability of receiving different grades once then the expected value is given by
E(X) = 1/p' = 46656/3125 = 14.93.
C. both a and b would be the best answer
Answer:
≈ 
%
Step-by-step explanation:
The person will wait for no more than 20 minutes if they arrive when the bus is going to stop in 20 minutes, which means that they must arrive 25 minutes after the previous bus stops. So the probability that the person will not wait for more than 20 minutes will be 
which is about 44.4%.
