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Finding the Fourth Proportional to 1,939.80, 2,910.10 and 642.18

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Solution

The fourth proportional to 1,939.80, 2,910.10 and 642.18 is: 963.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,939.80 : 2,910.10 = 642.18 : x
  2. Step 2: Convert to fraction form
    1,939.80/2,910.10 = 642.18/x
  3. Step 3: Cross multiply
    1,939.80x = 2,910.10 × 642.18
  4. Step 4: Simplify right side
    1,939.80x = 1,868,808.02
  5. Step 5: Solve for x
    x = 1,868,808.02/1,939.80
  6. Step 6: Final answer
    x = 963.40

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.