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Finding the Fourth Proportional to 91.78, 137.70 and 53.20

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Solution

The fourth proportional to 91.78, 137.70 and 53.20 is: 79.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.78 : 137.70 = 53.20 : x
  2. Step 2: Convert to fraction form
    91.78/137.70 = 53.20/x
  3. Step 3: Cross multiply
    91.78x = 137.70 × 53.20
  4. Step 4: Simplify right side
    91.78x = 7,325.81
  5. Step 5: Solve for x
    x = 7,325.81/91.78
  6. Step 6: Final answer
    x = 79.82

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.