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Finding the Fourth Proportional to 1,291.42, 1,936.13 and 641.65

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Solution

The fourth proportional to 1,291.42, 1,936.13 and 641.65 is: 961.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.42 : 1,936.13 = 641.65 : x
  2. Step 2: Convert to fraction form
    1,291.42/1,936.13 = 641.65/x
  3. Step 3: Cross multiply
    1,291.42x = 1,936.13 × 641.65
  4. Step 4: Simplify right side
    1,291.42x = 1,242,317.81
  5. Step 5: Solve for x
    x = 1,242,317.81/1,291.42
  6. Step 6: Final answer
    x = 961.98

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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.