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Finding the Fourth Proportional to 210.78, 316.44 and 138.78

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Solution

The fourth proportional to 210.78, 316.44 and 138.78 is: 208.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.78 : 316.44 = 138.78 : x
  2. Step 2: Convert to fraction form
    210.78/316.44 = 138.78/x
  3. Step 3: Cross multiply
    210.78x = 316.44 × 138.78
  4. Step 4: Simplify right side
    210.78x = 43,915.54
  5. Step 5: Solve for x
    x = 43,915.54/210.78
  6. Step 6: Final answer
    x = 208.35

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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.