Class 9 Probability from Data — practice questions with answers
Statistics · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
1. Empirical probability of an event E is calculated as:
A(Number of trials in which E happened) / (Total number of trials)
B(Total number of trials) / (Number of trials in which E happened)
C(Number of trials in which E happened) x (Total number of trials)
D(Total number of trials) - (Number of trials in which E happened)
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Answer: A) (Number of trials in which E happened) / (Total number of trials)
By definition, empirical (experimental) probability P(E) = number of trials in which E occurred divided by the total number of trials.
2. In a cricket match, batswoman Mithali hit 6 boundaries out of 30 balls she faced. The empirical probability that she did NOT hit a boundary on a ball is:
A54
B51
C306
D61
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Answer: A) 54
Balls with no boundary = 30 - 6 = 24. P(no boundary) = 3024 = 54.
3. A weather record of 30 days in July showed 18 rainy days in a town in Kerala. The empirical probability that a day in July is rainy is:
A53
B52
C10018
D31
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Answer: A) 53
P(rainy) = 3018 = 53.
4. A box of 50 light bulbs has some defective ones. Bulbs are drawn one by one (with replacement) and tested 200 times; a defective bulb is obtained 16 times. Based on this data, the empirical probability that a bulb is defective is:
A252
B5016
C251
D258
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Answer: A) 252
P(defective) = 20016 = 252.
5. A die was rolled and the empirical probabilities of the six faces in an experiment were 0.15, 0.18, 0.14, 0.17, 0.20 and p for faces 1 to 6 respectively. What is the value of p?
A0.66
B-0.34
C0.16
D0.32
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Answer: C) 0.16
All probabilities sum to 1: 0.15+0.18+0.14+0.17+0.20+p = 1, so 0.84 + p = 1, giving p = 0.16.