One pipe can fill a tank in 4 hours and another pipe can fill the tank in 6 hours. how long will it take if both pipes are used?

How many zeros does the function f(x)=4x3-x2+1 have

If value of cos330° is √3/2 then find tan165°.

Scores on the cognitive scale of the bayley-scales of infant and toddler development range from 1 to 19, with a standard deviation of 3. calculate the margin of error in estimating the true mean cognitive scale score, with 99% confidence, if there are 12 infants and toddlers in a sample.