To find the means before and after the rent change, we first need to calculate the mean of the original data set and then compute the mean after replacing the $1430 rent with $1115.
Step 1: Calculate the mean before the rent change
The original rent values are:
990, 879, 940, 1010, 950, 920, 1430
Calculate the sum of the original rents:
\[ \text{Sum} = 990 + 879 + 940 + 1010 + 950 + 920 + 1430 = 8190 \]
Calculate the mean:
\[ \text{Mean} = \frac{\text{Sum}}{\text{Number of tenants}} = \frac{8190}{7} \approx 1170 \]
Step 2: Change the rent from $1430 to $1115
Now, replace $1430 with $1115 and compute the new sum:
\[ \text{New Sum} = 990 + 879 + 940 + 1010 + 950 + 920 + 1115 = 6814 \]
Step 3: Calculate the mean after the rent change:
\[ \text{New Mean} = \frac{\text{New Sum}}{\text{Number of tenants}} = \frac{6814}{7} \approx 974 \]
Summary of results:
- Before the rent change, the mean rent was approximately 1170.
- After the rent change, the mean rent was approximately 974.
Conclusion
Looking at the options provided, we find:
A. Before the rent change, the mean was $990. After the rent change, the mean becomes $963
B. Before the rent change, the mean was $1017. After the rent change, the mean becomes $936
C. Before the rent changes, the mean is $1017. After the rent changes, the mean is $972.
None of the options provided are correct based on our calculations, but option C gets closer to what we computed after "973" however, it is still slightly off.
So the mean before the rent change is actually approximately 1170, and after it is approximately 974. If you want the option that is closest to a reasonable approximation based on your question, C is the closest.
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