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Finding the Fourth Proportional to 213.86, 320.80 and 77

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Solution

The fourth proportional to 213.86, 320.80 and 77 is: 115.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.86 : 320.80 = 77 : x
  2. Step 2: Convert to fraction form
    213.86/320.80 = 77/x
  3. Step 3: Cross multiply
    213.86x = 320.80 × 77
  4. Step 4: Simplify right side
    213.86x = 24,701.60
  5. Step 5: Solve for x
    x = 24,701.60/213.86
  6. Step 6: Final answer
    x = 115.50

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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.