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Finding the Fourth Proportional to 860.80, 1,291.20 and 515.20

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Solution

The fourth proportional to 860.80, 1,291.20 and 515.20 is: 772.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.80 : 1,291.20 = 515.20 : x
  2. Step 2: Convert to fraction form
    860.80/1,291.20 = 515.20/x
  3. Step 3: Cross multiply
    860.80x = 1,291.20 × 515.20
  4. Step 4: Simplify right side
    860.80x = 665,226.24
  5. Step 5: Solve for x
    x = 665,226.24/860.80
  6. Step 6: Final answer
    x = 772.80

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1.5x scale

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.