Solution :
a). The investment size -- Y
As we know, Z has higher a first cost alternative and also the incremental difference is 34,000. Therefore, the investment of Y is lower than that of Z by 34,000. Thus, the investment of Y = $ 92,000 - $ 34,000
= $ 58,000
b). Rate of return for Y
The question also mentions that the incremental 34,000 returned only 20 % while Z cumulatively generated 34%
Therefore, 34,000 at the rate of 20% return =
92,000 at the rate of 34% return =
The difference between the 92,000 and 32,000 is the investment of Y i.e. 58,000. Thus we check the difference between the 40800 and 123280 to find out how much 58000 (Y's investment ) would have generated.
123480 - 40800 = 82,480
Therefore, the return of Y is 42.03%