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Finding the Fourth Proportional to 499.78, 689.70 and 313.21

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Solution

The fourth proportional to 499.78, 689.70 and 313.21 is: 432.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    499.78 : 689.70 = 313.21 : x
  2. Step 2: Convert to fraction form
    499.78/689.70 = 313.21/x
  3. Step 3: Cross multiply
    499.78x = 689.70 × 313.21
  4. Step 4: Simplify right side
    499.78x = 216,020.94
  5. Step 5: Solve for x
    x = 216,020.94/499.78
  6. Step 6: Final answer
    x = 432.23

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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.