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  • Question
  • If three marbles are picked at random, what is the probability that two are blue and one is yellow?


  • Options
  • A. 3/91
  • B. 1/5
  • C. 18/455
  • D. 7/15

  • Correct Answer
  • 18/455 

    Explanation

    Ways of selection of two blue marbles = 4C2
    Ways of selection of one yellow marble = 3C1
    Ways of selection of three marbles = 15C3
    So, required probability = (4C2 x 3C1) / (15C3)
    = [4!/{2! (4 - 2)!} x 3!/{1! (3 - 1)!}] / [15! / {3! (15 - 3)!}]
    = [(4 x 3 x 2 x 1) / (2 x 1 x 2 x 1)] x [(3 x 2 x 1) / (1 x 2 x 1)] / [ (15 x 14 x 13 x 12!) / (3 x 2 x 12!)]
    = (6 x 3) / (5 x 7 x 13)
    = 18 / 455


  • More questions

    • 1. 
      Bus fare between Rajpur and Mirpur for one Adult is six times the fare of one child. If an adult's bus fare is ?114/-, how much amount will be paid by 4 adults and 5 children together for travelling the same distance?

    • Options
    • A. ? 505/-
    • B. ? 551/-
    • C. ?572/-
    • D. ?560/-
    • Discuss
    • 2. 
      Which of the following equations has real roots?

    • Options
    • A. 2x2 - 3x + 4 = 0
    • B. (x - 1) (2x - 5) = 0
    • C. 3x2 + 4x + 5 = 0
    • D. Cannot be determined
    • Discuss
    • 3. 
      If [a + (1/a)] 2 = 3 , what is the value of a 3 + (1/a) 3?

    • Options
    • A. 10?3/3
    • B. 0
    • C. 3?3
    • D. 6?3
    • Discuss
    • 4. 
      If one of the roots of quadratic equation 7y 2 - 50y + k = 0 is 7, then what is the value of k?

    • Options
    • A. 7
    • B. 1
    • C. 50/7
    • D. 7/50
    • Discuss
    • 5. 
      For what value of k, the equation x 2 + 2(k - 4) x + 2k = 0 has equal roots?

    • Options
    • A. 6 and 4
    • B. 8 and 2
    • C. 10 and 4
    • D. 12 and 2
    • Discuss
    • 6. 
      Two students A and B solve an equation of the from x 2 + px + q = 0. A starts with a wrong value of p and obtains the roots as 2 and 6. B starts with a wrong value of q and gets the roots as 2 and -9. What are the correct roots of the equation?

    • Options
    • A. 3 and - 4
    • B. - 3 and - 4
    • C. - 3 and 4
    • D. 3 and 4
    • Discuss
    • 7. 
      On a 20 % discount sale, an article costs 596 . What was the original price of the article?

    • Options
    • A. ? 720
    • B. ? 735
    • C. ? 745
    • D. ? 775
    • Discuss
    • 8. 
      A seller marks his goods 30% above their cost price but allows 15% discount for cash payment. His percentage of profit when sold in cash, is?

    • Options
    • A. 10.5%
    • B. 15%
    • C. 9%
    • D. 8.5%
    • Discuss
    • 9. 
      A dozen pair of socks quoted ? 80 are available at a discount of 10%. How many pair of socks can be bough for ? 24?

    • Options
    • A. 4
    • B. 5
    • C. 3
    • D. 6
    • Discuss
    • 10. 
      A shopkeeper sells not books at the rate of ? 457 each and earns a commission of 4% He also sells pencil boxes at the rate of ? 80 each and earns a commission of 20%. How much amount of commission will he he earn in two weeks, if he sells 10 notebooks and 6 pencil boxes a boy?

    • Options
    • A. ? 1956
    • B. ? 1586
    • C. ?1496
    • D. ? 1596
    • Discuss


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