Answer to Question #139363 in Statistics and Probability for Salvation

Question

The number of hours outside of class that students spend per week on a business statistics course is approximately normally distributed with a mean of 6 hours and a standard deviation 3.2 hours. Suppose there are 300 students registered for this course, approximately how many students work for more than four hours per week?

Answer 1

$Given \; that, μ=6, σ=3.2, then,\\ a) P(x>4) = P( Z >\frac{4-6}{3.2})\\ =P(Z>-0.63)\\=0.5+ P(0<Z<0.63)=\\ 0.5+0.2357=0.7357\\ \text{number of students}=300\times 0.7357\\ =220.71\approx 221\;student\\$