It is generally believed that nearsightedness affects about 1212 % of children in a certain region. A school district tests the vision of 160160 incoming kindergarten children. How many would be expected to be nearsighted? What is the standard deviation for the number of nearsighted children in this group?

Step-by-step explanation:

Total number of kindergarten children in that region that were tested is 160

It is generally believed that nearsightedness affects about 12% of children in a certain region. Therefore,

The expected number of kindergarten children expected to be nearsighted is

12/100 * 160 = 19

Probability of success, p = 0.12

Probability of failure, q = 1 - p = 1 - 0.12 = 0.88

Standard deviation = √npq = √ (160 * 0.12 * 0.88) = 4.11