There are 12 boys and 8 girls in a tuition centre. If three of them scored first mark, then what is the probability that one of the three is a girl and the other two are boys?
A. $$\frac{{14}}{{75}}$$
B. $$\frac{{22}}{{55}}$$
C. $$\frac{{44}}{{95}}$$
D. None of these
Answer: Option C
Solution(By Examveda Team)
Total number of students = 20Let S be the sample space
Then, n(S) = number of ways of three scored first mark
$$\eqalign{ & {\text{n}}\left( {\text{S}} \right) = {}^{20}{C_3} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{20 \times 19 \times 18}}{{2 \times 3}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 20 \times 19 \times 3 \cr} $$
Let, E be the event of 1 girl and 2 boys
Therefore, n(E) = number of possible of 1 girl out of 8 and 2 boys out of 12
$$\eqalign{ & {\text{n}}\left( {\text{E}} \right) = {}^8{C_1} \times {}^{12}{C_2} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{8 \times 12 \times 11}}{{1 \times 2}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 8 \times 6 \times 11 \cr} $$
Now, the required probability
$$\eqalign{ & = \frac{{{\text{n}}\left( {\text{E}} \right)}}{{{\text{n}}\left( {\text{S}} \right)}} \cr & = \frac{{8 \times 6 \times 11}}{{20 \times 19 \times 3}} \cr & = \frac{{44}}{{95}} \cr} $$
Related Questions on Probability
A. $$\frac{{1}}{{2}}$$
B. $$\frac{{2}}{{5}}$$
C. $$\frac{{8}}{{15}}$$
D. $$\frac{{9}}{{20}}$$
A. $$\frac{{10}}{{21}}$$
B. $$\frac{{11}}{{21}}$$
C. $$\frac{{2}}{{7}}$$
D. $$\frac{{5}}{{7}}$$
A. $$\frac{{1}}{{3}}$$
B. $$\frac{{3}}{{4}}$$
C. $$\frac{{7}}{{19}}$$
D. $$\frac{{8}}{{21}}$$
E. $$\frac{{9}}{{21}}$$
What is the probability of getting a sum 9 from two throws of a dice?
A. $$\frac{{1}}{{6}}$$
B. $$\frac{{1}}{{8}}$$
C. $$\frac{{1}}{{9}}$$
D. $$\frac{{1}}{{12}}$$
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