Let prime factorisation of n = (f1\(^x1\))*(f2^x2)*(f3^x3)....*(fm^xm)
Then, the number of factors of n = (x1 +1) * (x2 + 1) * (x3 + 1) * .... (xm + 1) = fn ~ (1)
Here fn is given as 24; (x1 +1) * (x2 + 1) * (x3 + 1) ....*(xm + 1) = 24, we are asked to find the maximum possible range in the number of distinct prime factors that n can have.
Maximum possible range of prime factors = maximum number of distinct prime factors that n can have - maximum number of distinct prime factors that n can have ~ (2)
m = number of distinct prime factors of n
1.) To find the maximum no. of distinct prime factors possible for n, that is to maximise "m",we express fn = 24 as a product of maximum possible number of its factors,
That is, fn = 2 * 2 * 2 * 3
Now from 1, we have (x1 +1) * (x2 + 1) * (x3 + 1) * .... (xm + 1) = fn;
∴ here m(max) = 4
That is, (x1 +1) = 2; x1 = 1
(x2 + 1)= 2; x2 = 1
(x3 + 1) = 2; x3 = 1
(x4 + 1) = 3; x4 = 2
2.) To find the minimum no. of distinct prime factors possible for n, that is to maximise "m", we express fn = 24 as a product of minimum possible number of its factors,
That is, fn = 24
Now from 1, we have (x1 +1) * (x2 + 1) * (x3 + 1) * .... (xm + 1) = fn;
∴ (x1 +1) = 24; x1 = 23
∴ m(min) = 1
Now we can see that the minimum and maximum possible prime factors possible for n are 1 and 4 respectively,
Therefore, from (2), we have Maximum possible range of prime factors = m(max) - m(min) = 4 - 1 = 3
The correct option is Option C