Answer:
270 students all together. First you divide 120 by the ratio of boys. That'll get you 30, then multiply 30 by 5 which is the girls ratio and you'll get 150. Finnaly add 150 + 120 then boom your answer
Let X be the number of boys in n selected births. Let p be the probability of getting baby boy on selected birth.
Here n=10. Also the male and female births are equally likely it means chance of baby boy or girl is 1/2
P(Boy) = P(girl) =0.5
p =0.5
From given information we have n =10 fixed number of trials, p is probability of success which is constant for each trial . And each trial is independent of each other.
So X follows Binomial distribution with n=10 and p=0.5
The probability function of Binomial distribution for k number of success, x=k is given as
P(X=k) = 
We have to find probability of getting 8 boys in n=10 births
P(X=8) = 
= 45 * 0.0039 * 0.25
P(X = 8) = 0.0438
The probability of getting exactly 8 boys in selected 10 births is 0.044
Let be M the set of the real numbers less thant 69
so we write it as follow M = { x∈R / x ∠ 69}
2.49 divied by 48 1/8
make 2.49 into an mixed number first
2 49/100.
make 2 49/100 into an improper fraction
Mutiply the whole number with the denominator
2*100= 200
Add 200 with the numerator. 200+49= 249
2 49/100= 249/100
48 1/8-make it into a improper fraction
48 1/8=385/8
249/100* 8/385
Answer: 0.05