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Finding the Fourth Proportional to 860.81, 1,291.20 and 211.55

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Solution

The fourth proportional to 860.81, 1,291.20 and 211.55 is: 317.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.81 : 1,291.20 = 211.55 : x
  2. Step 2: Convert to fraction form
    860.81/1,291.20 = 211.55/x
  3. Step 3: Cross multiply
    860.81x = 1,291.20 × 211.55
  4. Step 4: Simplify right side
    860.81x = 273,153.36
  5. Step 5: Solve for x
    x = 273,153.36/860.81
  6. Step 6: Final answer
    x = 317.32

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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.