<span>The best answer to this problem is 0.0823.
np = 48 * 1/4 = 12
The exactly 15 would be written as 14.5 to 15.5. You then plug those into you equation separately.
e1= (14.5-12)/3 = 0.833 and e2 =(15.5 - 12)/3 = 1.167)
p(0.833<e<1.167)= 0.0808</span>
