To find the marginal utility between the consumption of the 10th unit and the 11th unit, we need to follow these steps:
1. Identify the total utility when consuming 10 units of the good. According to the data provided, the total utility at 10 units is 120.
2. Identify the total utility when consuming 11 units of the good. The total utility at 11 units is 110.
3. Calculate the marginal utility. Marginal utility is the change in total utility that arises from consuming one additional unit of the good. We find this by subtracting the total utility at 10 units from the total utility at 11 units.
[tex]\[
\text{Marginal Utility} = \text{Total Utility at 11 units} - \text{Total Utility at 10 units}
\][/tex]
4. Plug in the numbers from the data provided:
[tex]\[
\text{Marginal Utility} = 110 - 120
\][/tex]
5. Perform the subtraction:
[tex]\[
\text{Marginal Utility} = -10
\][/tex]
So, the marginal utility when increasing consumption from 10 units to 11 units is [tex]\(-10\)[/tex]. This aligns with option (iii).
Thus, the correct answer is:
(iii) [tex]\(-10\)[/tex]
