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Finding the Fourth Proportional to 1,280.90, 1,767.69 and 721.33

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Solution

The fourth proportional to 1,280.90, 1,767.69 and 721.33 is: 995.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.90 : 1,767.69 = 721.33 : x
  2. Step 2: Convert to fraction form
    1,280.90/1,767.69 = 721.33/x
  3. Step 3: Cross multiply
    1,280.90x = 1,767.69 × 721.33
  4. Step 4: Simplify right side
    1,280.90x = 1,275,087.83
  5. Step 5: Solve for x
    x = 1,275,087.83/1,280.90
  6. Step 6: Final answer
    x = 995.46

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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.