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Finding the Fourth Proportional to 78.71, 107.90 and 74.80

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Solution

The fourth proportional to 78.71, 107.90 and 74.80 is: 102.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.71 : 107.90 = 74.80 : x
  2. Step 2: Convert to fraction form
    78.71/107.90 = 74.80/x
  3. Step 3: Cross multiply
    78.71x = 107.90 × 74.80
  4. Step 4: Simplify right side
    78.71x = 8,070.38
  5. Step 5: Solve for x
    x = 8,070.38/78.71
  6. Step 6: Final answer
    x = 102.53

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.