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Finding the Fourth Proportional to 928.62, 1,390.86 and 783.78

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Solution

The fourth proportional to 928.62, 1,390.86 and 783.78 is: 1,173.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.62 : 1,390.86 = 783.78 : x
  2. Step 2: Convert to fraction form
    928.62/1,390.86 = 783.78/x
  3. Step 3: Cross multiply
    928.62x = 1,390.86 × 783.78
  4. Step 4: Simplify right side
    928.62x = 1,090,128.25
  5. Step 5: Solve for x
    x = 1,090,128.25/928.62
  6. Step 6: Final answer
    x = 1,173.92

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.