The trick here is to use an appropriate substitution. Let u=a^3.
Then du/da=3a^2, and du=3a^2da.
We can now make two key substitutions: In (3a^2)da/(1+a^6), replace 3a^2 by du and a^6 by u^2.
Then we have the integral of du/(1+u^2).
Integrating, we get arctan u + c. Substituting a^3 for u, the final result (the integral in question) is arctan a^3 + c.
Check this by differentiation. if you find the derivative with respect to a of arctan a^3 + c, you MUST obtain the result 3a^2/(1+a^6).
Check the picture below.
notice that the point A is the center of the circle, and thus the ∡BAF is a central angle, and the arc BF gets its angle measurement from ∡BAF, in red.
now, notice, ∡BAF has a twin
vertical angle, namely ∡CAE in green, and the arc made by ∡CAE is congruent to BF.
If exactly one woman is to sit in one of the first 5 seats, then it means that 4 men completes the first 5 seats.
No of ways 4 men can be selected from 6 men = 6C4 = 15
No of ways 4 men can sit on 5 seats = 5P4 = 120
No of ways 1 woman can be selected fom 8 women = 8C1 = 8
No of ways 1 woman can sit on 5 seats = 5P1 = 5
No of ways <span>that exactly one woman is in one of the first 5 seats = 15 * 120 * 8 * 5 = 72,000
No of ways 14 people can be arranged in 14 seats = 14!
Probability that exactly one woman is in one of the first 5 seats = 72,000 / 14! = 0.0000008259 = 0.000083%
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Answer:
B
Step-by-step explanation:
It sounds most likely to the right answer
¯\_(ツ)_/¯
