Question

Two numbers are selected at
random from the set of 1 to
100. What is the probability of
both numbers being prime? *
O 4/33
O 5/33
O 7/33
O 2/33
16:​

Answer 1

Answer:4 )

Prime numbers between 1 to 35 = 2 , 3 , 5 , 7 , 11 , 13 , 17 , 19 , 23 , 29 , 31

Probability = ( Number of favourable outcomes ) / ( Total number of outcomes )

so,

Probability in this case =  

2 ) Probability that number is multiple of 7

Multiples of 7 between 1 to 35 = 7 , 14 , 21 , 28 , 35

So,

Probability =  =  

3 ) Probability that number is  multiple of 3 or 5

Multiples of 3 or 5 between 1 to 35 = 3 , 5 , 6 , 9 , 10, 12 , 15 , 18 , 20, 21 , 24 , 25, 27 , 30 , 33 , 35

So,

Probability =  

4 ) Probability that numbers are twin primes

Twin primes between 1 to 35 = {3, 5}, {5, 7}, {11, 13}, {17, 19}, {29, 31}

So,

Probability =   =  

Hence,

Answers are :

1 )  

2 )  

3)  

4 )