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Finding the Fourth Proportional to 1,261.54, 1,890.90 and 643.42

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Solution

The fourth proportional to 1,261.54, 1,890.90 and 643.42 is: 964.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,261.54 : 1,890.90 = 643.42 : x
  2. Step 2: Convert to fraction form
    1,261.54/1,890.90 = 643.42/x
  3. Step 3: Cross multiply
    1,261.54x = 1,890.90 × 643.42
  4. Step 4: Simplify right side
    1,261.54x = 1,216,642.88
  5. Step 5: Solve for x
    x = 1,216,642.88/1,261.54
  6. Step 6: Final answer
    x = 964.41

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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.