Out of 10 persons working on a project, 4 are graduates. If 3 are selected, what is the probability that there is at least one graduate among them?
Correct answer: D. 5/6Pakistan Studies Quiz
- A. 1/6
- B. 5/8
- C. 3/8
- D. 5/6Pakistan Studies Quiz
Explanation
Use the complement: the probability of selecting no graduate is C(6,3) ÷ C(10,3) = 20 ÷ 120 = 1/6, because 6 of the 10 people are non-graduates. Hence the probability of at least one graduate is 1 - 1/6 = 5/6. Students may choose 1/6 by reporting the probability of no graduate instead of its complement.
Last updated
About Ratio and Proportion
Ratios compare quantities in the same units, while proportions state that two ratios are equal. Problems cover simplification, division in a given ratio, direct and inverse variation, scale, and missing terms, with attention to the difference between a ratio and a fraction representing part of a whole.
Practise Arithmetic
1,060 free Arithmetic MCQs from Mathematics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Mathematics questions like this
Mathematics is on 67 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.