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Finding the Fourth Proportional to 72.39, 99.80 and 56.87

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Solution

The fourth proportional to 72.39, 99.80 and 56.87 is: 78.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.39 : 99.80 = 56.87 : x
  2. Step 2: Convert to fraction form
    72.39/99.80 = 56.87/x
  3. Step 3: Cross multiply
    72.39x = 99.80 × 56.87
  4. Step 4: Simplify right side
    72.39x = 5,675.43
  5. Step 5: Solve for x
    x = 5,675.43/72.39
  6. Step 6: Final answer
    x = 78.40

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.