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Finding the Fourth Proportional to 281, 421.50 and 129

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Solution

The fourth proportional to 281, 421.50 and 129 is: 193.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    281 : 421.50 = 129 : x
  2. Step 2: Convert to fraction form
    281/421.50 = 129/x
  3. Step 3: Cross multiply
    281x = 421.50 × 129
  4. Step 4: Simplify right side
    281x = 54,373.50
  5. Step 5: Solve for x
    x = 54,373.50/281
  6. Step 6: Final answer
    x = 193.50

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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.