Chapter 16: Probability

Example 4. Out of 400 bulbs in a box, 15 bulbs a defective. One ball is taken out at random from the box. Find the probability that the drawn bulb is not defective.

Solution:- Total number of bulbs = 400

Total number of defective bulb = 15

Total number of non-defective bulbs = 400-15

                                                                 = 385

P (not defective bulb) = 385/400

                                        = 77/80

Example 5. Find the probability of getting 53 Fridays in a leap year.

Solution:- No. of days in a leap year = 366

366 days = 52 weeks and 2 days.

A leap year must has 52 Fridays

The remaining two days can be

  1. Sunday an Monday
  2. Monday and Tuesday
  3. Tuesday and Wednesday
  4. Wednesday and Thursday
  5. Thursday and Friday
  6. Friday and Saturday
  7. Saturday and Sunday

Out of 7 case, 2 cases have Friday

P (53 Friday) = 2/7

 

Maths by Mr. M. P. Keshari
Privious Next
Subjects Maths (Part-1) by Mr. M. P. Keshari
Chapter 9 Circle
Chapter 10 Tangents to a circle
Chapter 11 Geometrical Construction
Chapter 12 Troigonometry
Chapter 13 Height and Distance
Chapter 14 Mensuration
Chapter 15 Statistics
Chapter 16 Probability
Chapter 17 Co-ordinate Geometry