Michael started a savings account with $300 . after 4 weeks , he had $350 dollars and after 9 weeks he had $400 . what is the rate of change of money in his savings account per week ?

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?

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.

Bob the builder is making 480kg of cement mix. this is made by cement, sand and gravel in the ratio 1: 3: 4