8. estimate each product and quotient, then calculate.
a) (-210) + (+7) b) (-36) * (-8)
c) (+492) + (-3) d) (+9) x (-15)
e) (-312) + (-4) f) (-28) * (+11)
9. calculate.
a) (+7) × (-3) - (-25) + (-5) b) (-39) - (+4) + (+2) + (453)
c) (-56) + (-9) x (+3) - (-76) d) (+42) + (-7) + (-b) (+2) me i'm lost me in number 8,9

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?