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Finding the Fourth Proportional to 1,391.80, 1,921.38 and 868.12

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Solution

The fourth proportional to 1,391.80, 1,921.38 and 868.12 is: 1,198.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.80 : 1,921.38 = 868.12 : x
  2. Step 2: Convert to fraction form
    1,391.80/1,921.38 = 868.12/x
  3. Step 3: Cross multiply
    1,391.80x = 1,921.38 × 868.12
  4. Step 4: Simplify right side
    1,391.80x = 1,667,988.41
  5. Step 5: Solve for x
    x = 1,667,988.41/1,391.80
  6. Step 6: Final answer
    x = 1,198.44

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Double scale
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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.