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Finding the Fourth Proportional to 91.40, 136.35 and 78.41

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Solution

The fourth proportional to 91.40, 136.35 and 78.41 is: 116.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.40 : 136.35 = 78.41 : x
  2. Step 2: Convert to fraction form
    91.40/136.35 = 78.41/x
  3. Step 3: Cross multiply
    91.40x = 136.35 × 78.41
  4. Step 4: Simplify right side
    91.40x = 10,690.52
  5. Step 5: Solve for x
    x = 10,690.52/91.40
  6. Step 6: Final answer
    x = 116.97

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.