Simple Seating Arrangement: 4 boys, 3 girls, in a row

T

Tina

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Joined
Mar 31, 2007
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16
Why is my answer wrong?

Four boys and three girls are seated in a row, at random, to watch a play.. What is the probability that a girl is seated at each end of the row?

I said 3/7. Three girls, seven all together? why is that wrong? Does anyone have the patience to explain before I rip more of my hair out?
 
Seat #
1 - 1 Girl amongst 3
2
3
4
5
6
7 - 1 Girl amongst 2

For 2-6, you have 5 people to sit, without regard to race, religion, sex, ethnicity, or further consideration.

Are you SURE you're in the right class? Have you been out sick? Is this a hopeless online course?
 
So the answer is 2/7. Believe it or not, only this chapter has driven me to you. I've finished the mid-term and this is the LAST math class I'll ever need. Apparently, tutors enjoy helping straight algegbra and keep asking why didn't I take the next Algebra class instead of choosing this, topic in math. It's an online and when I take the 2nd chance around for this quiz, I'd like to understand the choices i pick next instead of guessing.

Thank you so much for helping. I'm still online for a few, hope you'll be around. Thank you, thank you!!!!! tina
 
No the answer is 1/7.
\(\displaystyle \frac{{\left( 3 \right)\left( {5!} \right)\left( 2 \right)}}{{\left( {7!} \right)}} = \frac{1}{7}.\)

Three ways to start the row, two ways to end the row and (5!) ways to arrange the five people between.
 
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