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Finding the Fourth Proportional to 261.08, 391.63 and 78.50

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Solution

The fourth proportional to 261.08, 391.63 and 78.50 is: 117.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.08 : 391.63 = 78.50 : x
  2. Step 2: Convert to fraction form
    261.08/391.63 = 78.50/x
  3. Step 3: Cross multiply
    261.08x = 391.63 × 78.50
  4. Step 4: Simplify right side
    261.08x = 30,740.80
  5. Step 5: Solve for x
    x = 30,740.80/261.08
  6. Step 6: Final answer
    x = 117.74

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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.