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Finding the Fourth Proportional to 1,291.40, 1,811.80 and 1,291.40

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Solution

The fourth proportional to 1,291.40, 1,811.80 and 1,291.40 is: 1,811.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.40 : 1,811.80 = 1,291.40 : x
  2. Step 2: Convert to fraction form
    1,291.40/1,811.80 = 1,291.40/x
  3. Step 3: Cross multiply
    1,291.40x = 1,811.80 × 1,291.40
  4. Step 4: Simplify right side
    1,291.40x = 2,339,758.52
  5. Step 5: Solve for x
    x = 2,339,758.52/1,291.40
  6. Step 6: Final answer
    x = 1,811.80

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Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.