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Finding the Fourth Proportional to 99.21, 148.70 and 87

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Solution

The fourth proportional to 99.21, 148.70 and 87 is: 130.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.21 : 148.70 = 87 : x
  2. Step 2: Convert to fraction form
    99.21/148.70 = 87/x
  3. Step 3: Cross multiply
    99.21x = 148.70 × 87
  4. Step 4: Simplify right side
    99.21x = 12,936.47
  5. Step 5: Solve for x
    x = 12,936.47/99.21
  6. Step 6: Final answer
    x = 130.39

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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.