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Finding the Fourth Proportional to 744.20, 1,116.30 and 639.80

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Solution

The fourth proportional to 744.20, 1,116.30 and 639.80 is: 959.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    744.20 : 1,116.30 = 639.80 : x
  2. Step 2: Convert to fraction form
    744.20/1,116.30 = 639.80/x
  3. Step 3: Cross multiply
    744.20x = 1,116.30 × 639.80
  4. Step 4: Simplify right side
    744.20x = 714,208.74
  5. Step 5: Solve for x
    x = 714,208.74/744.20
  6. Step 6: Final answer
    x = 959.70

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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.