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Finding the Fourth Proportional to 211.20, 316.80 and 157.20

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Solution

The fourth proportional to 211.20, 316.80 and 157.20 is: 235.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.20 : 316.80 = 157.20 : x
  2. Step 2: Convert to fraction form
    211.20/316.80 = 157.20/x
  3. Step 3: Cross multiply
    211.20x = 316.80 × 157.20
  4. Step 4: Simplify right side
    211.20x = 49,800.96
  5. Step 5: Solve for x
    x = 49,800.96/211.20
  6. Step 6: Final answer
    x = 235.80

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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.