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Finding the Fourth Proportional to 991.72, 1,367.92 and 637.72

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Solution

The fourth proportional to 991.72, 1,367.92 and 637.72 is: 879.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.72 : 1,367.92 = 637.72 : x
  2. Step 2: Convert to fraction form
    991.72/1,367.92 = 637.72/x
  3. Step 3: Cross multiply
    991.72x = 1,367.92 × 637.72
  4. Step 4: Simplify right side
    991.72x = 872,349.94
  5. Step 5: Solve for x
    x = 872,349.94/991.72
  6. Step 6: Final answer
    x = 879.63

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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.