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Finding the Fourth Proportional to 743.40, 1,113.90 and 640.20

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Solution

The fourth proportional to 743.40, 1,113.90 and 640.20 is: 959.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    743.40 : 1,113.90 = 640.20 : x
  2. Step 2: Convert to fraction form
    743.40/1,113.90 = 640.20/x
  3. Step 3: Cross multiply
    743.40x = 1,113.90 × 640.20
  4. Step 4: Simplify right side
    743.40x = 713,118.78
  5. Step 5: Solve for x
    x = 713,118.78/743.40
  6. Step 6: Final answer
    x = 959.27

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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.