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  • Question
  • When six fairs coins are tossed simultaneously, in how many of the outcomes will at most three of the coins turn up as heads ?


  • Options
  • A. 15
  • B. 42
  • C. 16
  • D. 40

  • Correct Answer
  • 42 

    Explanation

    The question requires you to find number of the outcomes in which at most 3 coins turn up as heads.

    i.e., 0 coins turn heads or 1 coin turns head or 2 coins turn heads or 3 coins turn heads.

     

    The number of outcomes in which 0 coins turn heads is  6 C 0 =1 

    The number of outcomes in which 1 coin turns head is = 6 C 1 =6 

    The number of outcomes in which 2 coins turn heads is 6 C 2 =15 

    The number of outcomes in which 3 coins turn heads is 6 C 3 =20

     

    Therefore, total number of outcomes =1+6+15+20= 42 outcomes


  • More questions

    • 1. What is the average of four tenths and five thousandths

    • Options
    • A. 25002
    • B. 2502
    • C. 0.2025
    • D. none
    • Discuss
    • 2. Which number will come in place of question mark 7, 16, 36, 78, 144, ?

    • Options
    • A. 168
    • B. 196
    • C. 222
    • D. 256
    • Discuss
    • 3. Seven years ago, the average age of A, B and C was 51 years. If A is 3 years older than B and B is 3 years older then C then the present ages of A, B and C are ( in year)

    • Options
    • A. 61, 58 and 55
    • B. 54, 51, and 48
    • C. 55, 58, and 61
    • D. 48, 51 and 54
    • Discuss
    • 4. In the given figure, PQRS is a square inscribed in a circle of radius 4 cm. PQ is produced till point Y. From Y a tangent is drawn to the circle at point R. What is the length (in cm) of SY ?

    • Options
    • A. 4√10
    • B. 2√10
    • C. 6√10
    • D. 3√5
    • Discuss
    • 5. If V = 12R / (r + R) , then R =

    • Options
    • A. Vr / (12 - V)
    • B. Vr + (V /12 )
    • C. V
    • D. V / (r - 12 )
    • Discuss
    • 6. In a class of 60 students there are 20 girls who scored an average of 40 marks in the test, what is the average marks of the boys if the class average is 60 marks?

    • Options
    • A. 60
    • B. 70
    • C. 50
    • D. D)
    • Discuss
    • 7. Which of the fractions given below, when added to 5/8, gives 1?

    • Options
    • A. 6/16
    • B. 5/2
    • C. 6/24
    • D. 6/3
    • Discuss
    • 8. LCM of 80, 85, 90

    • Options
    • A. 11440
    • B. 11998
    • C. 12240
    • D. 12880
    • Discuss
    • 9. In a triangle, the distance of the centroid from the three vertices is 4cm, 6cm and 8cm respectively. Then the length of the smallest median is:

    • Options
    • A. 8
    • B. 7
    • C. 6
    • D. 5
    • Discuss
    • 10. In a mixture of 25 litres, the ratio of milk to water is 4:1. Another 3 litres of water is added to the mixture. The ratio of milk to water in the new mixture is

    • Options
    • A. 5:1
    • B. 5:2
    • C. 5:3
    • D. 5:4
    • Discuss


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