This GMAT quant practice question is a problem solving question in Descriptive Statistics. Concept: Compute the average for a set and parts of the set to determine the value of one element of the set. An easy to medium level difficulty question.
Explanatory AnswerVideo explanation provided for this question
Fill in the data given in the question in the standard framework as shown below. Most questions in averages can be solved by completing this standard framework. The sum of wages is computed as the product of the number of days and the average wage earned per day.
|Description||Number of days||Average Wages||Sum|
|All 15 days||15||$90||$1350|
|First 7 days||7||$87||$609|
|Last 7 days||7||$92||$644|
|14 days excluding 8th day||609 + 644 = $1253|
|8th day wage = Wages for all 15 - wages for 14 days excl 8th day||1350 - 1253 = $97|
The total wages earned during the 15 days that the worker worked = 15 * 90 = $ 1350.
The total wages earned during the first 7 days = 7 * 87 = $ 609.
The total wages earned during the last 7 days = 7 * 92 = $ 644.
Total wages earned during the 15 days = wages during first 7 days + wage on 8th day + wages during the last 7 days.
Or 1350 = 609 + wage on 8th day + 644
Wage on 8th day = 1350 - 609 - 644 = $ 97.
Choice D is the correct answer.