A box contains 3 blue marbles, 4 red, 6 green marbles and 2 yellow marbles. If four marbles are picked at random, what is the probability that none is blue?
Correct answer: B. 33/91
- A. 17/91
- B. 33/91
- C. 51/91
- D. 65/91Islamic Studies Quiz
Explanation
There are 12 non-blue marbles, so the favorable selections are C(12,4) = 495. The total selections are C(15,4) = 1365, giving 495/1365 = 33/91. Students often choose 17/91 by subtracting the number of blue marbles incorrectly instead of using combinations.
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 72 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.