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Finding the Fourth Proportional to 928.90, 1,392.30 and 380.78

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Solution

The fourth proportional to 928.90, 1,392.30 and 380.78 is: 570.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.90 : 1,392.30 = 380.78 : x
  2. Step 2: Convert to fraction form
    928.90/1,392.30 = 380.78/x
  3. Step 3: Cross multiply
    928.90x = 1,392.30 × 380.78
  4. Step 4: Simplify right side
    928.90x = 530,159.99
  5. Step 5: Solve for x
    x = 530,159.99/928.90
  6. Step 6: Final answer
    x = 570.74

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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.