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Finding the Fourth Proportional to 811.13, 1,215.96 and 317.21

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Solution

The fourth proportional to 811.13, 1,215.96 and 317.21 is: 475.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.13 : 1,215.96 = 317.21 : x
  2. Step 2: Convert to fraction form
    811.13/1,215.96 = 317.21/x
  3. Step 3: Cross multiply
    811.13x = 1,215.96 × 317.21
  4. Step 4: Simplify right side
    811.13x = 385,708.59
  5. Step 5: Solve for x
    x = 385,708.59/811.13
  6. Step 6: Final answer
    x = 475.52

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.