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Finding the Fourth Proportional to 979.50, 1,351.30 and 643.28

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Solution

The fourth proportional to 979.50, 1,351.30 and 643.28 is: 887.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.50 : 1,351.30 = 643.28 : x
  2. Step 2: Convert to fraction form
    979.50/1,351.30 = 643.28/x
  3. Step 3: Cross multiply
    979.50x = 1,351.30 × 643.28
  4. Step 4: Simplify right side
    979.50x = 869,264.26
  5. Step 5: Solve for x
    x = 869,264.26/979.50
  6. Step 6: Final answer
    x = 887.46

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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.