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Finding the Fourth Proportional to 78.80, 108.36 and 65.68

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Solution

The fourth proportional to 78.80, 108.36 and 65.68 is: 90.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.80 : 108.36 = 65.68 : x
  2. Step 2: Convert to fraction form
    78.80/108.36 = 65.68/x
  3. Step 3: Cross multiply
    78.80x = 108.36 × 65.68
  4. Step 4: Simplify right side
    78.80x = 7,117.08
  5. Step 5: Solve for x
    x = 7,117.08/78.80
  6. Step 6: Final answer
    x = 90.32

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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.