If cos(x) = Negative one-fourth and tan(x) < 0, what is sin(2x) ? Negative StartFraction StartRoot 15 EndRoot Over 4 EndFraction Negative StartFraction StartRoot 15 EndRoot Over 8 EndFraction StartFraction StartRoot 15 EndRoot Over 8 EndFraction StartFraction StartRoot 15 EndRoot Over 4 EndFraction

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?

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?

Since we have computer algebra systems that can solve polynomial division problems for us, why is it necessary to learn how to do these things by hand?