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Finding the Fourth Proportional to 1,385.94, 1,912.98 and 861.66

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Solution

The fourth proportional to 1,385.94, 1,912.98 and 861.66 is: 1,189.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,385.94 : 1,912.98 = 861.66 : x
  2. Step 2: Convert to fraction form
    1,385.94/1,912.98 = 861.66/x
  3. Step 3: Cross multiply
    1,385.94x = 1,912.98 × 861.66
  4. Step 4: Simplify right side
    1,385.94x = 1,648,338.35
  5. Step 5: Solve for x
    x = 1,648,338.35/1,385.94
  6. Step 6: Final answer
    x = 1,189.33

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1.5x scale

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.