There are approximately one billion smartphone users in the world today. In the United States the ages 13 to 55+of smartphone users approximately follow a normal distribution with approximate mean and standard deviationof 36.9 years and 13.9 years, respectively.

Determine the probability that a random smartphone user in the age range 13 to 55+ is younger than 23, or older than 64years old. Round to four decimal places.

a)0.3153

b)0.8157

c)0.8143

d)0.6847

Glass used in a one-waymirror should not distort a reflection. The glass should have a flat surfaceand a 1/4" thickness with athick coating of silvering but there are on average 2 flaws per every 10 square meters. What is the probability that a 3 meter by 4 meter sheet of this type of glass will contain at most 3 flaws? (round to 3 decimal points)

a)0.261

b)0.209

c)0.570

d)0.779