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Finding the Fourth Proportional to 261.55, 392.19 and 78.89

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Solution

The fourth proportional to 261.55, 392.19 and 78.89 is: 118.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.55 : 392.19 = 78.89 : x
  2. Step 2: Convert to fraction form
    261.55/392.19 = 78.89/x
  3. Step 3: Cross multiply
    261.55x = 392.19 × 78.89
  4. Step 4: Simplify right side
    261.55x = 30,941.05
  5. Step 5: Solve for x
    x = 30,941.05/261.55
  6. Step 6: Final answer
    x = 118.30

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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.