Home / 1,311.30-1,809.60-721.80

Finding the Fourth Proportional to 1,311.30, 1,809.60 and 721.80

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Solution

The fourth proportional to 1,311.30, 1,809.60 and 721.80 is: 996.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.30 : 1,809.60 = 721.80 : x
  2. Step 2: Convert to fraction form
    1,311.30/1,809.60 = 721.80/x
  3. Step 3: Cross multiply
    1,311.30x = 1,809.60 × 721.80
  4. Step 4: Simplify right side
    1,311.30x = 1,306,169.28
  5. Step 5: Solve for x
    x = 1,306,169.28/1,311.30
  6. Step 6: Final answer
    x = 996.09

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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.