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Finding the Fourth Proportional to 1,238.39, 1,708.95 and 678.86

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Solution

The fourth proportional to 1,238.39, 1,708.95 and 678.86 is: 936.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,238.39 : 1,708.95 = 678.86 : x
  2. Step 2: Convert to fraction form
    1,238.39/1,708.95 = 678.86/x
  3. Step 3: Cross multiply
    1,238.39x = 1,708.95 × 678.86
  4. Step 4: Simplify right side
    1,238.39x = 1,160,129.25
  5. Step 5: Solve for x
    x = 1,160,129.25/1,238.39
  6. Step 6: Final answer
    x = 936.80

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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.