Praxis Core Academic Skills for Educators: Mathematics (5733)Number and QuantityMedium
A project manager is estimating task durations. Task X is estimated to take between 3.5 and 4.5 hours. Task Y is estimated to take between 2.75 and 3.25 hours. What is the maximum possible combined time, in hours, for both tasks?
- A7.75 hours
- B7.00 hours
- C8.00 hours
- D6.25 hours
Show answer & explanationAnswer & explanation
Correct answer: A. 7.75 hours
To find the maximum possible combined time, you must add the maximum estimated times for each task. Max time for Task X = 4.5 hours. Max time for Task Y = 3.25 hours. Combined maximum time = 4.5 + 3.25 = 7.75 hours.
Why the other options are wrong
- B. This might come from adding the lower bound of one and the upper bound of the other, or an arithmetic error.
- C. This might result from an arithmetic error or incorrect rounding.
- D. This is the minimum combined time (3.5 + 2.75).
Estimation with Ranges
When dealing with quantities defined by ranges (minimum and maximum values), calculations for combined minimums or maximums involve adding the respective bounds.
- To find maximum combined value, add individual maximums.
- To find minimum combined value, add individual minimums.
- This principle applies to addition and subtraction of estimated values.
Memory trick: For max, add the max; for min, add the min. Don't mix 'em in!