Question 7.7. The weights of bags of ready-to-eat salad are normally distributed with a mean of 290 grams and a standard deviation of 10 grams. What percent of the bags weigh less than 280 grams?
(Points : 3)
34%

13.5%

16%

36.5%

Question

Question 7.7. The weights of bags of ready-to-eat salad are normally distributed with a mean of 290 grams and a standard deviation of 10 grams. What percent of the bags weigh less than 280 grams?
(Points : 3)
       34%

       13.5%

       16%

       36.5%

anonymous · Answer

$$\begin{align*} P(X<280)&=P\left(\frac{X-290}{10}<\frac{280-290}{10}\right)\ &=P(Z<-1) \end{align*}$$ You can determine this probability using a table or http://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule

anonymous · Answer

@hartnn