# NCERT Class 9 Solutions: Probability (Chapter 15) Exercise 15.1-Part 1

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Q-1 In a cricket match, a batswoman hits a boundary 6 times out of 30 balls she plays. Find the probability that she did not hit a boundary.

Solution:

Total numbers of balls

Numbers of boundary

Numbers of time she didn't hit boundary

Probability she did not hit a boundary (P)

Q-2 1500 families with 2 children were selected randomly and the following data were recorded:

Number of girls in a family | 2 | 1 | 0 |

Number of families | 475 | 814 | 211 |

Compare the probability of family, chosen at random, having

I. 2 girls

II. 1 girl

III. No girl

**Solution I:**

Total numbers of families

Numbers of families having girls

Probability

**Solution II:**

Total numbers of families

Numbers of families having girls

Probability

**Solution III:**

Total numbers of families

Numbers of families having no girls

Probability

Sum of the probability =

Yes, the sum of these probabilities is

Q-3 In a particular section of class IX, 40 students were asked about the months of their birth and the following graph was prepared for the data so obtained. Find the probability that a student of class was born in August.

**{point.y}**"},"credits":{"enabled":false},"xAxis":{"categories":["Jan.","Feb.","Mar.","Apr.","May.","June.","July.","Aug.","Sep.","Oct.","Nov.","Dec"],"title":{"text":"Month of birth"}},"yAxis":{"type":"linear","title":{"text":" Number of students"},"stackLabels":{"enabled":true,"style":{"fontWeight":"bold","color":"gray"}}},"plotOptions":{"series":{"allowPointSelect":true,"cursor":"pointer"}},"legend":{"floating":false,"backgroundColor":"white","borderColor":"silver","borderWidth":1,"shadow":true,"align":"right"},"series":[{"type":"column","name":"Month of birth Vs Number of students","data":[3,4,2,2,5,1,2,6,3,4,4,4],"colors":[{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#f7a35c"],[1,"rgb(171,87,16)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#8085e9"],[1,"rgb(52,57,157)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#f15c80"],[1,"rgb(165,16,52)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#e4d354"],[1,"rgb(152,135,8)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#2b908f"],[1,"rgb(0,68,67)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#f45b5b"],[1,"rgb(168,15,15)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#91e8e1"],[1,"rgb(69,156,149)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#7cb5ec"],[1,"rgb(48,105,160)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#434348"],[1,"rgb(0,0,0)"]]},{"linearGradient":{"x1":0,"y1":0,"x2":0,"y2":1},"stops":[[0,"#90ed7d"],[1,"rgb(68,161,49)"]]}]}]}

Solution:

Total numbers of students

Numbers of students born in August

Required probability