Q4.(12) Assume the time (in hours) spent on playing game every day for a teenager is approximately normal. The mean time is 1.5 hours, the standard deviation is 0.5 hours.

1.(4) Randomly select one teenager, find the probability that the time he/she spends on playing game is more than 2 hours.

2.(4) Randomly select 10 teenagers, find the probability exactly 3 teenagers who spend more than 2 hours on playing game.

3.(4) Assume random samples with sample size of 16, find the probability that the sample mean time spent on playing games is less than 1.2 hours