Answered

If Dominik completes a project by himself, it will take him 8 hours. Working with Katarina, it will take them 5 hours.




Rate (part/hour)Time (hours)Part of Project Completed

Dominik
$\frac{1}{8}$5?

Katarina
$r$5$5 r$






If they work together, what is the missing value from the table that represents the part of the project Dominik will complete?


A$8 r$
B8(5)
C$\frac{1}{8} r$
D$\frac{1}{8}(5)$

Verified Answer :

  • Define the work formula: \(\text{Work} = \text{Rate} \times \text{Time}\).
  • Identify Dominik's rate as \(\frac{1}{8}\) part/hour and time as \(5\) hours.
  • Calculate the work: \(\frac{1}{8} \times 5 = \frac{1}{8}(5)\).
  • Final answer: \(\boxed{\frac{1}{8}(5)}\).

Explanation

  1. Analysis of the Work Problem

The problem asks us to determine the missing value in a table representing the portion of a project completed by Dominik, who works at a rate of \(\frac{1}{8}\) part/hour for 5 hours. The fundamental relationship in work-related problems is defined by the formula \(\text{Work} = \text{Rate} \times \text{Time}\). In this context, the rate of work is given as \(\frac{1}{8}\) part per hour, and the duration Dominik works is 5 hours. Our objective is to calculate the work completed by Dominik using this information.

  1. Calculating the Completed Work

To find the missing value, we apply the work formula. Dominik's rate is \(R_D = \frac{1}{8}\) part/hour and the time he spends working is \(T = 5\) hours. Therefore, the part of the project completed by Dominik is given by the product:
\[\text{Part of Project Completed} = R_D \times T = \frac{1}{8} \times 5 = \frac{1}{8}(5)\]
This calculation represents the portion of the task Dominik finishes within the 5-hour period.

  1. Selecting the Correct Option

Comparing our result \(\frac{1}{8}(5)\) with the provided options, we can clearly see that it matches the fourth option. The other options, such as \(8r\), \(8(5)\), and \(\frac{1}{8}r\), do not correctly represent the multiplication of Dominik's rate and his time. Thus, the missing value is \(\frac{1}{8}(5)\).

Examples

Consider a factory worker assembling parts for a machine. If the worker can assemble \(\frac{1}{20}\) of a machine per hour and they work for 6 hours, the total portion of the machine assembled would be \(\frac{1}{20} \times 6 = \frac{6}{20}\) or 30% of the machine. Understanding this relationship helps in project management, planning production schedules, and estimating the time required to complete various tasks effectively.