Question No. 9 of 10 | 1 Marks
A laboratory contains 6 test tubes of chemical A, 3 test tube of chemical B and 4 test tube of
chemical C. Three test tubes of them are drawn at random, what is the probability that the
three are not of the same chemical?
Answers
Answer:
Step-by-step explanation:
12
Probability that the selected three are NOT of the same chemical = 0.91
No of test tubes of A = 6
No of test tubes of B = 3
No of test tubes of C = 4
Total no. of test tubes = 6 + 3 + 4
= 13
Probability of 3 selected chemicals are A=
= 6/13×5/12×4/11
= 120/1716
= 0.07
Probability of 3 selected chemicals are B=
= 3/13×2/12×1/11
= 6/1716
= 0.0035
Probability of 3 selected chemicals are C=
= 4/13×3/12×2/11
= 24/1716
= 0.014
Probability that the selected three are of the same chemical
= 0.07+0.0035+0.014
= 0.0875
Probability that the selected three are NOT of the same chemical = 1 - 0.0875
= 0.91
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