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Finding the Fourth Proportional to 1,291.30, 1,935.94 and 642.49

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Solution

The fourth proportional to 1,291.30, 1,935.94 and 642.49 is: 963.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.30 : 1,935.94 = 642.49 : x
  2. Step 2: Convert to fraction form
    1,291.30/1,935.94 = 642.49/x
  3. Step 3: Cross multiply
    1,291.30x = 1,935.94 × 642.49
  4. Step 4: Simplify right side
    1,291.30x = 1,243,822.09
  5. Step 5: Solve for x
    x = 1,243,822.09/1,291.30
  6. Step 6: Final answer
    x = 963.23

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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.