KVPY2013MathematicsSets and Relations
For an integer n let S _ n = n +1, n +2, , n +18 . Which of the following is true for all n 10 ?
Options
- AS_ n has a multiple of 19
- BS_ n has a prime
- CS ₀^ n has at least four multiples of 5
- DS_ n ^ n has at most six primes
Correct answer
D. S_ n ^ n has at most six primes
Step-by-step solution
n+1, n+2, n+18 (A) False, if n=19 (C) False if n =15 16 to 33 20,25,30 only three multiples of 5 (D) no. of odd integers in S_ n =9 every third odd integer is multiple of 3 so maximum prime no. =6 .