Please help! I've got nooo idea what to do!

4. The average and standard deviation of the amount of Goods and Services Tax remitted by all performance artists in a twelve month period were $6.69 thous and $1.67 thous respectively. If a sample of 116 artists was taken, find the average value (in thous dollars) below which only 1% of taxes would lie.

5. The length of time of long-distance phone calls has a variance of 38.4 minutes squared. It is also known that 7% of calls last longer than 42.4 minutes. Find the mean assuming the distribution closely approximates a normal distribution

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