(7) This is a question on joint families, externalities, and fertility choice. Suppose that Ram and Rani are the heads of a nuclear family, making their fertility decisions. For simplicity, assume away gender bias and issues of child survival. The following table details the costs and benefits (in dollars, say) of different numbers of children. Number of children Total benefit ($) Additional cost One 500 100 Two 750 100 Three 840 100 Four 890 100 Five 930 100 Six 950 100 Seven 960 100 Eight 960 100 (a) Based on the information in the table, how many children would Ram and Rani have in order to maximize their net benefit? (b) Now consider two identical nuclear families: Ram and Rani (as above), and Mohan and Mona. Ram and Mohan are brothers and the two couples form a joint family. Both couples have exactly the same costs and benefits of having children as in the table. Now suppose that 50% of the upbringing costs of each child (e.g., child care) can be passed on to the other family. Each couple makes independent decisions, taking only its own welfare into account. Now how many children will each couple have