The wingspans of a common species of housefly are normally distributed with a mean of 0.5mm. Suppose that a biologist regularly collects random samples of 20 of these houseflies and calculates the sample mean wingspan from each sample. What will be the shape of the sampling distribution of the sample mean wingspan?

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).