Six friends go out to eat. the bill, including tax and tip, came out to $84.00. two of the friends paid one–half of the bill. the other four friends paid the other half. how much money did each of the four friends have to pay? assume each of the four friends paid the same amount.

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?