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Finding the Fourth Proportional to 912, 1,257.60 and 678.72

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Solution

The fourth proportional to 912, 1,257.60 and 678.72 is: 935.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    912 : 1,257.60 = 678.72 : x
  2. Step 2: Convert to fraction form
    912/1,257.60 = 678.72/x
  3. Step 3: Cross multiply
    912x = 1,257.60 × 678.72
  4. Step 4: Simplify right side
    912x = 853,558.27
  5. Step 5: Solve for x
    x = 853,558.27/912
  6. Step 6: Final answer
    x = 935.92

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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.