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Finding the Fourth Proportional to 1,291.49, 1,934.80 and 642.68

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Solution

The fourth proportional to 1,291.49, 1,934.80 and 642.68 is: 962.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.49 : 1,934.80 = 642.68 : x
  2. Step 2: Convert to fraction form
    1,291.49/1,934.80 = 642.68/x
  3. Step 3: Cross multiply
    1,291.49x = 1,934.80 × 642.68
  4. Step 4: Simplify right side
    1,291.49x = 1,243,445.98
  5. Step 5: Solve for x
    x = 1,243,445.98/1,291.49
  6. Step 6: Final answer
    x = 962.80

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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.