smallest 2 digit number divisible by 4 is 12
so we want:
12, 16, 20, 24, 28, 32, 36, 40,.... ,96
this is an arithmetic sequence with
a = 12, d=4
what term number is 96 ?
a + (n-1)d = 96
12 + (n-1)(4) = 96
4n - 4 = 84
4n = 88
n = 22
There would be 22 terms divisible by 4
BUT, we could not have formed 20, 40, 60 and 80
so there are 18 such terms
#2
number of ways with no restrictions
= 4! = 24
consider the 2 girls a single entity
number of ways to arrange with the girls side by side = 3! = 6
So the number of ways the two girls are not together = 18
How many of the 2-digit numbers, that can be formed by using the digits 1,2,3,.......,9 without repeating any digit, are divisible by4?
If 2 boys and 2 girls are to be arranged in a row so that the girls are not next to each other, how many possible arrangements are there?
A selection test consists of two parts, A and B. 75% of the candidates cleared part A and 60% cleared part B. 20% failed to clear either. What is the % of candidates who cleared one of the parts but failed to clear the other?
Pls help me
2 answers
14 i think