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Finding the Fourth Proportional to 1,186.94, 1,638 and 689.65

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Solution

The fourth proportional to 1,186.94, 1,638 and 689.65 is: 951.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,186.94 : 1,638 = 689.65 : x
  2. Step 2: Convert to fraction form
    1,186.94/1,638 = 689.65/x
  3. Step 3: Cross multiply
    1,186.94x = 1,638 × 689.65
  4. Step 4: Simplify right side
    1,186.94x = 1,129,642.61
  5. Step 5: Solve for x
    x = 1,129,642.61/1,186.94
  6. Step 6: Final answer
    x = 951.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.