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Finding the Fourth Proportional to 261.39, 391.91 and 99.05

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Solution

The fourth proportional to 261.39, 391.91 and 99.05 is: 148.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.39 : 391.91 = 99.05 : x
  2. Step 2: Convert to fraction form
    261.39/391.91 = 99.05/x
  3. Step 3: Cross multiply
    261.39x = 391.91 × 99.05
  4. Step 4: Simplify right side
    261.39x = 38,816.23
  5. Step 5: Solve for x
    x = 38,816.23/261.39
  6. Step 6: Final answer
    x = 148.50

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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.