At a local school, there are 17 girls and 21 boys in seventh grade and 14 girls and 12 boys in eighth grade. The school principal randomly selects an eighth grader and a seventh grader for a citywide competition. What is the probability that the students she selects are both boys? Write your answer as a fraction in lowest terms.
Please Explain how to solve this problem in layman's terms.
2007-05-30 11:54:11 · 3 answers · asked by Thegrinch57 1 in Science & Mathematics ➔ Mathematics
I Checked the answer, and its much harder then that... the answer is 63/274
2007-05-30 12:25:03 · update #1
The answers given previously are wrong.
Correct solution:
Probability of picking a boy in grade 7 = 21/38.
Probability of picking a boy in grade 8 = 12/26.
Probability of both of these happening is the
product of the two probabilities. (Assuming
these events are independent--neither influences
the outcome of the other.)
So, P(both are boys) = 21/38 * 12/26,
which reduces to 63/247.
It looks like you transposed the last 2 digits
of the denominator when you gave the answer.
Hope that helps!!
2007-05-30 14:15:10 · answer #1 · answered by steiner1745 7 · 0⤊ 0⤋
well...
7th grade- 17 girls 21 boys total 38 kids
8th grade- 14 girls 12 boys total 26 kids
31 girls 33 boys total 64 kids
so... the probability picking boys out of bothe grades out of all children is..
2 becasue it's two boys she's picking out, out of 64 total kids.. 2 out of 64 reduced to 1 out of 32. so probablilty is 1/32
that s my reasoning.... see if it makes sense to you hope it helps.
2007-05-30 19:04:23 · answer #2 · answered by GodisLove 3 · 0⤊ 1⤋
you put the number you are looking for (2) ove the number of possibilities (17+21+14+12) (64) which makes 2/64 and reduce...
2007-05-30 19:00:40 · answer #3 · answered by spudnick_93 1 · 0⤊ 1⤋