By what distance, x2, should the second child compress the spring so that the marble lands in the middle of the box? (assume that height of the box is negligible, so that there is no chance that the marble will hit the side of the box before it lands in the bottom.)]

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?