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Finding the Fourth Proportional to 782.12, 1,079.70 and 520.40

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Solution

The fourth proportional to 782.12, 1,079.70 and 520.40 is: 718.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    782.12 : 1,079.70 = 520.40 : x
  2. Step 2: Convert to fraction form
    782.12/1,079.70 = 520.40/x
  3. Step 3: Cross multiply
    782.12x = 1,079.70 × 520.40
  4. Step 4: Simplify right side
    782.12x = 561,875.88
  5. Step 5: Solve for x
    x = 561,875.88/782.12
  6. Step 6: Final answer
    x = 718.40

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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.