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Finding the Fourth Proportional to 761.49, 1,140.21 and 639.99

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Solution

The fourth proportional to 761.49, 1,140.21 and 639.99 is: 958.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    761.49 : 1,140.21 = 639.99 : x
  2. Step 2: Convert to fraction form
    761.49/1,140.21 = 639.99/x
  3. Step 3: Cross multiply
    761.49x = 1,140.21 × 639.99
  4. Step 4: Simplify right side
    761.49x = 729,723.00
  5. Step 5: Solve for x
    x = 729,723.00/761.49
  6. Step 6: Final answer
    x = 958.28

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Double scale
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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.