15. Last year Joan's salary was $18,000. If she receives a $900 raise for this year, what percent of last year's salary is her raise?
Answer: B
Joan's raise is 5% of last year's salary.
To find the percent of last year's salary that Joan's raise represents, we calculate the ratio of the raise to the original salary and then convert it to a percentage. The calculation shows that her $900 raise is 5% of her $18,000 salary.
A) 2%
This option is incorrect because 2% of $18,000 is $360, which is significantly less than the $900 raise that Joan received. Therefore, this percentage does not accurately represent the raise.
B) 5%
This option is correct as it accurately reflects the calculation of the raise as a percentage of last year's salary. Dividing the $900 raise by the $18,000 salary and multiplying by 100 yields 5%, confirming that this is the correct answer.
C) 20%
This option is incorrect because 20% of $18,000 is $3,600, which greatly exceeds the $900 raise that Joan received. Thus, this percentage does not correspond to the raise amount.
D) 50%
This option is incorrect as well. A raise of 50% would imply an increase of $9,000 (which is half of $18,000), far greater than the actual raise of $900. Therefore, this percentage misrepresents the raise amount.
Conclusion
The correct answer is 5%, as it accurately describes the relationship between Joan's raise and her last year's salary. All other options miscalculate the percentage, either underestimating or overestimating the amount, demonstrating a misunderstanding of percentage calculations in this context.