Solution

To compare the performance of the utility functions, compute the utility of each bundle under each candidate function:

Bundle	J	B	Rank	J*B	J*J+B
1	1	1	worst	1	2
2	2	1	second	2	5
3	1	2	third	2	3
4	3	1	best	3	10

The first utility function is wrong: it assigns the same value to bundles 2 and 3 even though the individual says that bundle 2 is better than bundle 3. The second utility function works: it ranks the bundles the same way the individual did.