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  • Question

  • The average age of 30 students in a class is 12 years. The average age of a group of 5 of the students is 10 years and that of another group of 5 them is 14 years. The average age of the remaining students is?


  • Options
  • A. 8 years
  • B. 10 years
  • C. 12 years
  • D. 14 years

  • Correct Answer
  • 12 years 

    Explanation

    Let average of the remaining student be y.
    Then from questions ( 5 x 10 ) + ( 5 x 14) + 20y = 30 x 12
    ? 50 + 70 + 20y = 360
    ? 20y = 360 ? 120
    ? 20y = 240
    ? y = 12.

    • More questions

    • 1. The sum of three numbers is 252. If the first number is thrice the second and third number is two-third of the first, then the second number is

    • Options
    • A. 41
    • B. 21
    • C. 42
    • D. 84
      • Discuss
    • 2. The sum of squares of three positive integers is 323. If the sum of squares of two numbers is twice the third, their product is

    • Options
    • A. 255
    • B. 260
    • C. 265
    • D. 270
      • Discuss
    • 3. If the sum of squares of two real numbers is 41 and their sum is 9. Then the sum of cubes of these two numbers is

    • Options
    • A. 169
    • B. 209
    • C. 189
    • D. 198
      • Discuss
    • 4. If x+y+z = 1, 1/x + 1/y + 1/z = 1 and xyz = -1, then x3+y3+z3 is equal to

    • Options
    • A. -1
    • B. 1
    • C. -2
    • D. 2
      • Discuss
    • 5. Twenty one times of a positive number is less than its square by 100. The value of the positive number is

    • Options
    • A. 25
    • B. 26
    • C. 42
    • D. 41
      • Discuss
    • 6. In a group of 6 boys and 4 girls, four children are to be selected. In how many different ways can they be selected such that at least one boy should be there?

    • Options
    • A. 209
    • B. 290
    • C. 200
    • D. 208
      • Discuss
    • 7. The product of two numbers is 48. If one number equals "The number of wings of a bird plus 2 times the number of fingers on your hand divided by the number of wheels of a Tricycle". Then the other number is

    • Options
    • A. 9
    • B. 10
    • C. 12
    • D. 18
      • Discuss
    • 8. Two numbers whose sum is 84 can not be in the ratio

    • Options
    • A. 5:7
    • B. 13:8
    • C. 1:3
    • D. 3:2
      • Discuss
    • 9. If (x+1/x) = 5, then the value of 5xx2+5x+1 ?

    • Options
    • A. 1/3
    • B. 1/4
    • C. 1/2
    • D. 1/5
      • Discuss
    • 10. How many natural numbers are there between 1000 to 2000, which when divided by 341 leaves remainder 5?

    • Options
    • A. 3
    • B. 2
    • C. 4
    • D. 1
      • Discuss

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