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Finding the Fourth Proportional to 1,311.68, 1,810.77 and 920.78

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Solution

The fourth proportional to 1,311.68, 1,810.77 and 920.78 is: 1,271.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.68 : 1,810.77 = 920.78 : x
  2. Step 2: Convert to fraction form
    1,311.68/1,810.77 = 920.78/x
  3. Step 3: Cross multiply
    1,311.68x = 1,810.77 × 920.78
  4. Step 4: Simplify right side
    1,311.68x = 1,667,320.80
  5. Step 5: Solve for x
    x = 1,667,320.80/1,311.68
  6. Step 6: Final answer
    x = 1,271.13

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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.