22 How many prime numbers are there which are less than 100 and greater than 3 such that they are

Ans is - e.None of the above
6 years agoHelpfull: Yes(1) No(1)
none of the above
ans is 2
5,7,11,13,17,19,23,29,31,37,41,47,56,59,61,67,71,73,79,83,89,97
5 years agoHelpfull: Yes(1) No(0)
Let the number be N.
So N = 4x + 1 = 5y - 1
=> x=5y?24
y = 2 satisfies the equation. So minimum number satisfies both the equations is 9 and general format of the numbers which satisfies the equation = k. LCM (4, 5) + 9 = 20k + 9.
Now by putting values 1, 2, 3 . . . . for k, we get 29, 49, 69, 89. Of which only 29, 89 are primes.

So the answer was 2 numbers.
6 years agoHelpfull: Yes(0) No(6)
none of the above is the answer
6 years agoHelpfull: Yes(0) No(0)
e-None of the above
5 years agoHelpfull: Yes(0) No(0)
(1 to 100)=25
but less than from 100 and greater from 3
so 1,2,3 are prime numbers.
25-3=22
then 4x + 15y -1=22
5 years agoHelpfull: Yes(0) No(1)
The primes p such that 3 < p < 100 and of the form 4x+1 are 5, 13, 17, 29, 37, 41, 53, 61, 73, 89 and 97. These are eleven in number.

The primes of the form 5y-1 are 19, 29, 59, 79 and 89 and these are five in number. Only two of these viz. 29 and 89 are in both the lists. Both the lists taken together do not exhaust all the primes in this range, and 7, 11, 23, 31, 43, 47, 67, 71 and 83 do not appear in either of the lists.
4 years agoHelpfull: Yes(0) No(0)
answer is e
4 years agoHelpfull: Yes(0) No(0)

22. How many prime numbers are there which are less than 100 and greater than 3 such that they are of the following forms?
a. 4x + 15y - 1
b. 11
c. 12
d. 7
e. None of the above