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Finding the Fourth Proportional to 1,311.38, 1,810.21 and 869.12

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Solution

The fourth proportional to 1,311.38, 1,810.21 and 869.12 is: 1,199.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.38 : 1,810.21 = 869.12 : x
  2. Step 2: Convert to fraction form
    1,311.38/1,810.21 = 869.12/x
  3. Step 3: Cross multiply
    1,311.38x = 1,810.21 × 869.12
  4. Step 4: Simplify right side
    1,311.38x = 1,573,289.72
  5. Step 5: Solve for x
    x = 1,573,289.72/1,311.38
  6. Step 6: Final answer
    x = 1,199.72

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.