Let C denote the positively oriented boundary of the half disk 0 ≤ r ≤ 1, 0 ≤ θ ≤ π, and let f (z) be a continuous function defined on that half disk by writing f (0) = 0 and using the branch f (z) = √ reiθ/2 r > 0,−π 2 < θ < 3π 2 of the multiple-valued function z1/2. Show that C f (z) dz = 0 by evaluating separately the integrals of f (z) over the semicircle and the two radii which make up C. Why does the Cauchy–Goursat theorem not apply here?

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?