It appears that about 1400 1400 students were exposed. What is the probability that at least 75 % 75% of these students develop infections if not treated? (Fortunately, whooping cough is much less serious after infancy.)

i did it myself and i got 4.2 (b) hope its right

step-by-step explanation:

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

eventually after a few more steps, your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x