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Finding the Fourth Proportional to 928.40, 1,390.80 and 516.80

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Solution

The fourth proportional to 928.40, 1,390.80 and 516.80 is: 774.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.40 : 1,390.80 = 516.80 : x
  2. Step 2: Convert to fraction form
    928.40/1,390.80 = 516.80/x
  3. Step 3: Cross multiply
    928.40x = 1,390.80 × 516.80
  4. Step 4: Simplify right side
    928.40x = 718,765.44
  5. Step 5: Solve for x
    x = 718,765.44/928.40
  6. Step 6: Final answer
    x = 774.20

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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.