Question
Three colleagues, M, N, and O, have an average age of
27. Ten years ago, their ages were in the ratio of 4:6:7. What is the average age of M and N today?Solution
Sum of their present ages = 3 × 27 = 81 Sum of their ages before 10 years = 81-30 = 51 Let their ages 10 years ago were 4x, 6x and 7x Then, 4x+6x+7x = 51 17x = 51 x = 3 their ages 10 years ago were 12, 18, 21 present age of M = 12+10 = 22 present age of N = 18+10 = 28 average of present age of M and N = (28+22)/2 = 25
In how many ways can the letters of the word VOWEL can be arranged so that all the consonants occupy odd places, vowels come on even places?
- How many four-letter words without repetition having exactly two vowels can be formed by using the letters of the word "VINTAGER"?
- A school wants to form a committee of 5 students from 6 boys and 4 girls. How many ways can the committee be formed if it must contain at least 3 boys?
How many different words can be formed with the letters of the word PRACTICE such that each of the word begin with E and ends with R?
In a bag there are 4 red balls, 3 green balls, and 5 blue balls. If one ball is drawn at random from the bag, what is the probability of drawing a green...
How many four-letter words without repetition having exactly two vowels can be formed by using the letters of the word "SEMINAR"?
A committee of 4 members is to be formed from 5 men and 4 women such that at least one woman is included. In how many ways can this be done?
In how many ways can the letters of the word ENGINEERING be arranged?
How many 4-digit even numbers can be formed using digits 1, 2, 3, 4, 5, 6 without repetition?
In how many ways can the letters of the word ‘BANANA’ be arranged?
Relevant for Exams:
