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Finding the Fourth Proportional to 1,315.87, 1,815.30 and 811.28

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Solution

The fourth proportional to 1,315.87, 1,815.30 and 811.28 is: 1,119.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,315.87 : 1,815.30 = 811.28 : x
  2. Step 2: Convert to fraction form
    1,315.87/1,815.30 = 811.28/x
  3. Step 3: Cross multiply
    1,315.87x = 1,815.30 × 811.28
  4. Step 4: Simplify right side
    1,315.87x = 1,472,721.12
  5. Step 5: Solve for x
    x = 1,472,721.12/1,315.87
  6. Step 6: Final answer
    x = 1,119.20

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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.