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Finding the Fourth Proportional to 678.68, 1,013.43 and 640.23

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Solution

The fourth proportional to 678.68, 1,013.43 and 640.23 is: 956.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.68 : 1,013.43 = 640.23 : x
  2. Step 2: Convert to fraction form
    678.68/1,013.43 = 640.23/x
  3. Step 3: Cross multiply
    678.68x = 1,013.43 × 640.23
  4. Step 4: Simplify right side
    678.68x = 648,828.29
  5. Step 5: Solve for x
    x = 648,828.29/678.68
  6. Step 6: Final answer
    x = 956.02

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.