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Finding the Fourth Proportional to 813.42, 1,220.40 and 640.17

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Solution

The fourth proportional to 813.42, 1,220.40 and 640.17 is: 960.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.42 : 1,220.40 = 640.17 : x
  2. Step 2: Convert to fraction form
    813.42/1,220.40 = 640.17/x
  3. Step 3: Cross multiply
    813.42x = 1,220.40 × 640.17
  4. Step 4: Simplify right side
    813.42x = 781,263.47
  5. Step 5: Solve for x
    x = 781,263.47/813.42
  6. Step 6: Final answer
    x = 960.47

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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.