No of ways of selecting 2 sections out of 4 is 4C2 = 6
Number of ways of selecting questions = 7C3 * 7C6 or 7C4*7C5 or 7C5*7C4 or 7C6*7C3
=2 (7C3 * 7C6 or 7C4*7C5 ) = 2(35*7 + 35*21) = 70*28 = 1960
So total required ways = 6*1960 = 11760
Let x=log42+log432
X=log441/2+log445/2
X=1/2+5/2
X=6/2
X=3
Take LCM of 6, 15, 21 and 24 i.e. 840
Hence smallest 3 digit number divisible by 6, 15, 21 and 24 is 840
We know 4 digit largest number is 9999 so we divide this number by LCM OF 6, 15, 21 AND 24 i.e. 840
9999/840=11(759/840)
9999-759=9240
7*6C4
7*6*5/2
105
Let the other multiplier be x.
41x – 14x = 135
27x = 135
x = 5