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Finding the Fourth Proportional to 921.92, 1,271.30 and 642.47

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Solution

The fourth proportional to 921.92, 1,271.30 and 642.47 is: 885.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.92 : 1,271.30 = 642.47 : x
  2. Step 2: Convert to fraction form
    921.92/1,271.30 = 642.47/x
  3. Step 3: Cross multiply
    921.92x = 1,271.30 × 642.47
  4. Step 4: Simplify right side
    921.92x = 816,762.54
  5. Step 5: Solve for x
    x = 816,762.54/921.92
  6. Step 6: Final answer
    x = 885.94

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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.