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Finding the Fourth Proportional to 1,109.28, 1,531.06 and 643.80

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Solution

The fourth proportional to 1,109.28, 1,531.06 and 643.80 is: 888.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,109.28 : 1,531.06 = 643.80 : x
  2. Step 2: Convert to fraction form
    1,109.28/1,531.06 = 643.80/x
  3. Step 3: Cross multiply
    1,109.28x = 1,531.06 × 643.80
  4. Step 4: Simplify right side
    1,109.28x = 985,696.43
  5. Step 5: Solve for x
    x = 985,696.43/1,109.28
  6. Step 6: Final answer
    x = 888.59

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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.