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Finding the Fourth Proportional to 1,261.24, 1,891.80 and 645.20

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Solution

The fourth proportional to 1,261.24, 1,891.80 and 645.20 is: 967.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,261.24 : 1,891.80 = 645.20 : x
  2. Step 2: Convert to fraction form
    1,261.24/1,891.80 = 645.20/x
  3. Step 3: Cross multiply
    1,261.24x = 1,891.80 × 645.20
  4. Step 4: Simplify right side
    1,261.24x = 1,220,589.36
  5. Step 5: Solve for x
    x = 1,220,589.36/1,261.24
  6. Step 6: Final answer
    x = 967.77

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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.