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Finding the Fourth Proportional to 775.49, 1,070.15 and 421.40

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Solution

The fourth proportional to 775.49, 1,070.15 and 421.40 is: 581.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    775.49 : 1,070.15 = 421.40 : x
  2. Step 2: Convert to fraction form
    775.49/1,070.15 = 421.40/x
  3. Step 3: Cross multiply
    775.49x = 1,070.15 × 421.40
  4. Step 4: Simplify right side
    775.49x = 450,964.94
  5. Step 5: Solve for x
    x = 450,964.94/775.49
  6. Step 6: Final answer
    x = 581.53

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.