True or False: The confidence interval obtained is valid only if the distribution of the population of salary offers is normal

Click on the graphic until you find the right quotient. (36xa - 30xb) ÷ (-6x2)

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?

What multiplys to be 1 but adds up to be 4