Question

1.A number is chosen at random from s={1,......,520}. what is the probability that is divisible by 5 or 7?
2.A fair coin is flipped 4 times.let x be the number of heads appearing out of the four trials.calculate the following probabilities:
a) no head will appear
b) at least two will appear
c) less than two heads will appear
d) at most heads 2 will appear

Answer 1

Since , we have =

divisibility occurred by 5

520÷5=104times

divisibility by 7=

518÷7=74 times because 518 is the max no. divide by 520

Probability can be occurred =74+104=178

Then P(e)=178/520

=89/260Ans