If a silver alloy that costs $4.50 an ounce is going to be mixed with 10 ounces of a silver
alloy that costs $8 an ounce to make a mixture
that costs $7 an ounce, how many ounces of
the $4.50 an ounce alloy must be used?

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

The area of square garden is 300m squared. how long is the diagonal?

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?