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Finding the Fourth Proportional to 212.80, 317.60 and 187.20

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Solution

The fourth proportional to 212.80, 317.60 and 187.20 is: 279.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.80 : 317.60 = 187.20 : x
  2. Step 2: Convert to fraction form
    212.80/317.60 = 187.20/x
  3. Step 3: Cross multiply
    212.80x = 317.60 × 187.20
  4. Step 4: Simplify right side
    212.80x = 59,454.72
  5. Step 5: Solve for x
    x = 59,454.72/212.80
  6. Step 6: Final answer
    x = 279.39

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.