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Finding the Fourth Proportional to 100.34, 138.21 and 86.50

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Solution

The fourth proportional to 100.34, 138.21 and 86.50 is: 119.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.34 : 138.21 = 86.50 : x
  2. Step 2: Convert to fraction form
    100.34/138.21 = 86.50/x
  3. Step 3: Cross multiply
    100.34x = 138.21 × 86.50
  4. Step 4: Simplify right side
    100.34x = 11,955.01
  5. Step 5: Solve for x
    x = 11,955.01/100.34
  6. Step 6: Final answer
    x = 119.15

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.