Sumaya can manufacture a spark plug in 13 minutes. When her friend Leonardo helps her, it takes them 5.32 minutes. Using a rational equation, which of the following correctly calculates the rate Leonardo manufactures spark plugs, rounded to the nearest hundredth?

Responses

5.32 minutes
5.32 minutes

2.44 minutes
2.44 minutes

9.01 minutes
9.01 minutes

69.16 minutes

1 answer

To find Leonardo's manufacturing rate, we can set up a rational equation based on the times it takes for Sumaya and Leonardo to work individually and together.

Let:

  • \( S \) be the rate at which Sumaya manufactures spark plugs (in spark plugs per minute)
  • \( L \) be the rate at which Leonardo manufactures spark plugs (in spark plugs per minute)

Sumaya can manufacture a spark plug in 13 minutes, so her rate is: \[ S = \frac{1 \text{ spark plug}}{13 \text{ minutes}} = \frac{1}{13} \text{ spark plugs per minute} \]

Let’s assume Leonardo takes \( x \) minutes to make one spark plug, so his rate is: \[ L = \frac{1 \text{ spark plug}}{x \text{ minutes}} = \frac{1}{x} \text{ spark plugs per minute} \]

When they work together, they can manufacture a plug in 5.32 minutes. This gives us their combined rate: \[ \text{Combined Rate} = \frac{1 \text{ spark plug}}{5.32 \text{ minutes}} = \frac{1}{5.32} \text{ spark plugs per minute} \]

According to the formula for combined rates: \[ S + L = \text{Combined Rate} \] Substituting the values for \( S \) and \( L \): \[ \frac{1}{13} + \frac{1}{x} = \frac{1}{5.32} \]

Now, let's solve for \( x \):

  1. First, we can find a common denominator for the left side: \[ \frac{x + 13}{13x} = \frac{1}{5.32} \]

  2. Cross-multiplying gives us: \[ 5.32(x + 13) = 13x \]

  3. Distributing the 5.32: \[ 5.32x + 69.16 = 13x \]

  4. Rearranging the equation: \[ 69.16 = 13x - 5.32x \] \[ 69.16 = 7.68x \]

  5. Solving for \( x \): \[ x = \frac{69.16}{7.68} \approx 9.01 \]

Therefore, Leonardo's time to manufacture one spark plug is approximately \( 9.01 \) minutes.

The answer is: 9.01 minutes