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Finding the Fourth Proportional to 1,109.70, 1,531.08 and 643.95

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Solution

The fourth proportional to 1,109.70, 1,531.08 and 643.95 is: 888.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,109.70 : 1,531.08 = 643.95 : x
  2. Step 2: Convert to fraction form
    1,109.70/1,531.08 = 643.95/x
  3. Step 3: Cross multiply
    1,109.70x = 1,531.08 × 643.95
  4. Step 4: Simplify right side
    1,109.70x = 985,938.97
  5. Step 5: Solve for x
    x = 985,938.97/1,109.70
  6. Step 6: Final answer
    x = 888.47

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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.