(1) As mentioned earlier, according to the meaning of the question, μ= 150μ is the intersection of the vertical lines in the middle of the normal distribution diagram on the horizontal axis, that is, the value of the midpoint. Do you know σ? Do you know the standard error of 625? σ=25, which is derived from √ 625 = 25; 100=μ-2σ, where did this come from? You know μ-2 σ =150-2× 25 =100.

The title requires "estimated consumption x", and within a range, this range is (100, 150), that is, 100.

p(μ-2σ& lt； X≤μ), in this question, is it actually? p( 100 & lt； X≤ 150), because 100

Use it later? 1000×P( 100 & lt； X≤ 150) get the number of consumers in 100~ 150 yuan, and find the number of winners in box A. Note: the winning probability of box A has nothing to do with the normal division probability of this question! Is another independent probability distribution. What is this? Only the balls with numbers 1, 2, 3 win the prize, and the balls without numbers don't win the prize. There are 1, 2, 3 and 4 balls numbered * * 10 respectively, and only 1 and 2 can win the prize.

-Listen, it's nice of you to understand *-~