Ascientist wishes to estimate the mean breaking strength of a certain type of steel rod within 3.0 psi with 95% confidence. based on experience with a similar type of steel, she believes the standard deviation is approximately 15.0 psi in individual breaking strengths. how many steel rods should she test?

Suppose that the price p, in dollars, and the number of sales, x, of a certain item follow the equation 4 p plus 4 x plus 2 pxequals56. suppose also that p and x are both functions of time, measured in days. find the rate at which x is changing when xequals2, pequals6, and startfraction dp over dt endfraction equals1.5.