/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 31 Working together, two people can... [FREE SOLUTION] | 91Ó°ÊÓ

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Working together, two people can cut a large lawn in 2 hr. One person can do the job alone in 1 hr less time than the other. How long (to the nearest tenth) would it take the faster worker to do the job?

Short Answer

Expert verified
The faster worker would take approximately 3.6 hours to do the job alone.

Step by step solution

01

- Define Variables

Let the time taken by the faster worker to cut the lawn alone be denoted by \( t \) hours. Then, the slower worker takes \( t + 1 \) hours to cut the lawn alone.
02

- Determine Work Rates

The work rate of the faster worker is \( \frac{1}{t} \) lawns per hour, and the work rate of the slower worker is \( \frac{1}{t + 1} \) lawns per hour.
03

- Combine Work Rates

Working together, their combined work rate is the sum of their individual work rates. So, \( \frac{1}{t} + \frac{1}{t+1} = \frac{1}{2} \) since they can complete the lawn in 2 hours together.
04

- Solve the Equation

Solve the equation \( \frac{1}{t} + \frac{1}{t+1} = \frac{1}{2} \). Multiply both sides by \( 2t(t+1) \) to clear denominators: \( 2(t+1) + 2t = t(t+1) \). This simplifies to \( 2t + 2 + 2t = t^2 + t \). Combined terms give \( 4t + 2 = t^2 + t \). Set to zero to form a quadratic equation: \( t^2 - 3t - 2 = 0 \).
05

- Solve the Quadratic Equation

Use the quadratic formula \( t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \) where \( a = 1 \), \( b = -3 \), and \( c = -2 \). Calculate the discriminant: \( (-3)^2 - 4(1)(-2) = 9 + 8 = 17 \). Therefore, \( t = \frac{3 \pm \sqrt{17}}{2} \). Calculate the positive root: \( t = \frac{3 + \sqrt{17}}{2} \), approximately \( t = 3.6 \) hours.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

quadratic equations
Quadratic equations are a type of polynomial equation in which the highest exponent of the variable is 2. The general form of a quadratic equation is \[ ax^2 + bx + c = 0 \] where \( a, b, \) and \( c \) are constants and \( x \) is the variable. Solving quadratic equations often involves using the quadratic formula: \[ x = \frac{-b \,\pm \,\sqrt{b^2 - 4ac}}{2a} \] In this problem, we ended up with the quadratic equation \[ t^2 - 3t - 2 = 0 \] representing the relationship between the time taken by two workers when combined versus individually. We solved it using the quadratic formula, which gave us the value of \( t \). This helps determine how long the faster worker will take alone.
work rate problems
Work rate problems involve determining the amount of work done over time by different entities working together or individually. In our problem, each worker has a specific rate at which they can complete a task. To solve these types of problems, we use the formula: \[ \text{Work rate} = \frac{1}{\text{Time}} \] For example, if the slower worker takes \( t + 1 \) hours, their work rate is \( \frac{1}{t + 1} \). When combining work rates, you add individual rates together:\[ \frac{1}{t} + \frac{1}{t+1} \] Their combined rate must equal the total work done (one lawn) over the combined time (2 hours). Hence, we get: \[ \frac{1}{t} + \frac{1}{t+1} = \frac{1}{2} \]
math problem-solving
Math problem-solving involves several steps to break down and approach a problem logically. Here's a simple strategy that we applied in this exercise:
  • Define the variables: Assign symbols to unknowns to simplify the representation.
  • Translate words to equations: Convert descriptions into mathematical expressions.
  • Combine equations: Use relevant formulas to merge and simplify them.
  • Solve for the unknown: Use algebraic techniques such as the quadratic formula.
  • Verify your solution: Substitute back to ensure correctness.
By following these steps methodically, we can tackle most algebra word problems and work rate problems efficiently. The key is to stay organized and work through each part systematically.

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Most popular questions from this chapter

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