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Finding the Fourth Proportional to 678.60, 1,012.14 and 643.86

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Solution

The fourth proportional to 678.60, 1,012.14 and 643.86 is: 960.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.60 : 1,012.14 = 643.86 : x
  2. Step 2: Convert to fraction form
    678.60/1,012.14 = 643.86/x
  3. Step 3: Cross multiply
    678.60x = 1,012.14 × 643.86
  4. Step 4: Simplify right side
    678.60x = 651,676.46
  5. Step 5: Solve for x
    x = 651,676.46/678.60
  6. Step 6: Final answer
    x = 960.32

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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.