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Finding the Fourth Proportional to 100.19, 138.16 and 79.40

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Solution

The fourth proportional to 100.19, 138.16 and 79.40 is: 109.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.19 : 138.16 = 79.40 : x
  2. Step 2: Convert to fraction form
    100.19/138.16 = 79.40/x
  3. Step 3: Cross multiply
    100.19x = 138.16 × 79.40
  4. Step 4: Simplify right side
    100.19x = 10,969.90
  5. Step 5: Solve for x
    x = 10,969.90/100.19
  6. Step 6: Final answer
    x = 109.49

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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.