5/16
You have to simplify both sides of the equation, then isolating the variable.
If you change 1/4 so that the denominators of both fractions are the same by mutiplying 4x3 for the bottom and 3x1 for the top and then add 5/12 and 3/12 to get 8/12 and then for it to be a whole number, you need 4/12 to complete the whole which is the fraction of children at the bleachers at the basketball game (4/12) .
Solution :
Let x be student will be left handed
P = 0.09
Using the normal approximation to binomial distribution,
a). n = 108,
μ = np = 9.72


= 2.9741
Required probability,
P(x=8) = P(7.5 < x < 8.5)


Using z table,
= P(z<-0.41)-P(z<-0.75)
= 0.3409-0.2266
= 0.1143
b). P(x=12) = P(11.5 < x < 12.5)


Using z table,
= P(z< 0.94)-P(z< 0.60)
= 0.8294 - 0.7257
= 0.1006
Seven, I think. That's what I found somewhere else.