Number System
The sum of the ages of a son and father is 65 years. After 5 years the age of father will be double of the age of son. What is the age of son ?
Let the age of the son be x and the age of the father be y.Therefore, x + y = 65 ..........(i)or, 2 x (x + 5) = (y + 5)or, 2x + 10 = y + 5or, 2x - y = 5 ...................(ii)From equations (i) and (ii), x = 20, y = 45
For a number to be divisible by 4, the number formed by the last two digits of that number must be divisible by 4.For a number to be divisible by 9, the sum of its digits must be divisible by 9.Among the choices, choices (a) and (b) are divisible by 4 but of the first two choices, only choice (b) is divisible by 9.Hence choice (b) is divisible by both 4 and 9.
Since the number is greater than the number obtained on reversing the digits, so the ten's digit is greater than the unit's digit.Let the ten's and unit's digits be 2x and x respectively.Then, (10 * 2x + x) - (10x + 2x) = 369x = 36x = 4Required difference = (2x + x) - (2x - x) = 2x = 8.
There are total eight letters ∴ n(S) = 8PB = 8!As all vowels should come together we assume them as one letter. Here E, I, O and U together are taken as one, so the number of letter is 4 + 1 = 5 and it can be arranged in 5P5 = 5! ways and the vowels can be arranged in 4! ways among themselves∴ n(E) = 4! x 5!∴ P(E) = 4!5! / 8! = 4x3x2x5! / 8x7x6x5! = 4x3x2 / 8x7x6 = 1/14
EXAMIANS