Solution:From I:
LCM of p and q = 144
Product of p and q = 3456
HCF of p and q = (Product of p and q)/(LCM of p and q)
= 3456/144 = 24
Statement I alone is not sufficient.
From II:
HCF of q and r = 12
Let q = 12a and r = 12b [a and b are co-prime]
r - q = 12b - 12a = 60
b - a = 5
Possible pair of values of (a, b) = (1, 6), (2, 7), (3, 8), (4, 9), and so on.
Possible pair of values of (q, r) = (12, 72), (24, 84), (36, 96), and (48, 108)
Statement II alone is not sufficient.
From III:
LCM of p, q and r = 432
Statement III alone is not sufficient.
From I and II:
Possible pair of values of (q, r) = (12, 72), (24, 84), (36, 96), and (48, 108)
Possible pair of values of p = 288, 144, 96, and 72
Possible LCM of p and q = 288, 144, 288, and 144
Case 1: When p = 144, q = 24, and r = 84
HCF of p and q = 24
HCF of three numbers p, q, and r = 12
Case 2: When p = 72, q = 48, and r = 108
HCF of p and q = 24
HCF of three numbers p, q, and r = 12
In both the cases we are getting the same HCF.
Statements I and II together are sufficient.
From I and III:
Let p = 24m and q = 24n [m and n are co-prime.]
LCM of p and q = 24mn = 144
mn = 6
Possible value of (m, n) = (1, 6), (6, 1), (2, 3), and (3, 2)
Statements I and III together are not sufficient.
From II and III:
Possible pair of values of (q, r) = (12, 60), (24, 84), (36, 96), and (48, 108)
LCM of p, q, and r = 432
Statements II and III together are not sufficient.