Question

Difficulty: Very hardBasic Algebraic Expressions and One-Step Equations

A manufacturing assembly line produces a batch of BB electronic components in hh hours. To increase efficiency, a new assembly line is installed that can produce the same batch of components in 13\frac{1}{3} of the time. Which of the following expressions represents the rate, in components per hour, at which the new assembly line produces these components?

  1. 3Bh\frac{3B}{h}Answer
  2. B
    B3h\frac{B}{3h}
  3. C
    3hB\frac{3h}{B}
  4. D
    3Bh3Bh
  5. E
    h3B\frac{h}{3B}

Answer

The expression 3Bh\frac{3B}{h} represents the rate of production of the new assembly line.
The correct answer shows that the rate of production is the number of components divided by the new time, which is one-third of the original time. Since the original time is hh hours, the new time is h3\frac{h}{3} hours. Dividing the number of components BB by h3\frac{h}{3} yields B÷h3=B×3h=3BhB \div \frac{h}{3} = B \times \frac{3}{h} = \frac{3B}{h} components per hour.

Step-by-Step Solution

1
Determine the time it takes for the new assembly line to produce the batch of components.
The new assembly line takes h3\frac{h}{3} hours.
The problem states the new line produces the batch in 13\frac{1}{3} of the original time, hh.
2
Set up the algebraic expression for the rate of production in components per hour.
Rate=Total ComponentsTotal Time=Bh3\text{Rate} = \frac{\text{Total Components}}{\text{Total Time}} = \frac{B}{\frac{h}{3}}
Rate is defined as quantity produced divided by time elapsed.
3
Simplify the fraction to find the final expression.
Rate=B×3h=3Bh\text{Rate} = B \times \frac{3}{h} = \frac{3B}{h}
Dividing by a fraction is equivalent to multiplying by its reciprocal.

Key Concept

Formulating algebraic rate expressions from word problems
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