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Finding the Fourth Proportional to 78.70, 108.52 and 72.08

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Solution

The fourth proportional to 78.70, 108.52 and 72.08 is: 99.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.70 : 108.52 = 72.08 : x
  2. Step 2: Convert to fraction form
    78.70/108.52 = 72.08/x
  3. Step 3: Cross multiply
    78.70x = 108.52 × 72.08
  4. Step 4: Simplify right side
    78.70x = 7,822.21
  5. Step 5: Solve for x
    x = 7,822.21/78.70
  6. Step 6: Final answer
    x = 99.40

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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.