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Finding the Fourth Proportional to 811.16, 1,215.78 and 486.32

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Solution

The fourth proportional to 811.16, 1,215.78 and 486.32 is: 728.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.16 : 1,215.78 = 486.32 : x
  2. Step 2: Convert to fraction form
    811.16/1,215.78 = 486.32/x
  3. Step 3: Cross multiply
    811.16x = 1,215.78 × 486.32
  4. Step 4: Simplify right side
    811.16x = 591,258.13
  5. Step 5: Solve for x
    x = 591,258.13/811.16
  6. Step 6: Final answer
    x = 728.90

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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.