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Finding the Fourth Proportional to 620.80, 931.20 and 611.20

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Solution

The fourth proportional to 620.80, 931.20 and 611.20 is: 916.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.80 : 931.20 = 611.20 : x
  2. Step 2: Convert to fraction form
    620.80/931.20 = 611.20/x
  3. Step 3: Cross multiply
    620.80x = 931.20 × 611.20
  4. Step 4: Simplify right side
    620.80x = 569,149.44
  5. Step 5: Solve for x
    x = 569,149.44/620.80
  6. Step 6: Final answer
    x = 916.80

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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.