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Finding the Fourth Proportional to 907.92, 1,252.20 and 643.28

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Solution

The fourth proportional to 907.92, 1,252.20 and 643.28 is: 887.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    907.92 : 1,252.20 = 643.28 : x
  2. Step 2: Convert to fraction form
    907.92/1,252.20 = 643.28/x
  3. Step 3: Cross multiply
    907.92x = 1,252.20 × 643.28
  4. Step 4: Simplify right side
    907.92x = 805,515.22
  5. Step 5: Solve for x
    x = 805,515.22/907.92
  6. Step 6: Final answer
    x = 887.21

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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.