Mr. Moore finds on any given day 7% of students have not done their homework. Find the probability that 5 out of his 30 students did not do their homework.

Question

Its a probability problem and I have to find the probability of how many students don't do their homework

Answer 1

the Poisson formula will work well here, which is Probability = [(e-^μ)(μ^x)/x] where e is a constant equal to 2.718, μ = expected number, and x = projected number

 

in this case, μ is equal to 30 x 7% = 30 x 0.07 = 2.1

x = 5

 

then P = [(2.718^-2.1)(2.1⁵)/5] = [(0.122)(40.8)/5] = (4.97/5) ≅ 0.995 

 

because we expect that this situation will NOT occur,

we subtract our result from 1 to get 1 - 0.995  ≅ 0.005