An economy produces capital goods and consumer goods. Five combinations on its production possibilities curve are A (100 capital goods, 0 consumer goods), B (90, 25), C (70, 45), D (40, 60) and E (0, 70). The figures are invented. Calculate the opportunity cost of one extra unit of consumer goods when the economy moves from B to C, and when it moves from C to D. What do the two results show about the shape of the curve, and can the economy produce the combination 80 capital goods and 50 consumer goods?

Skills drill (not an IB exam format).