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Finding the Fourth Proportional to 1,390.10, 1,917.43 and 891.95

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Solution

The fourth proportional to 1,390.10, 1,917.43 and 891.95 is: 1,230.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.10 : 1,917.43 = 891.95 : x
  2. Step 2: Convert to fraction form
    1,390.10/1,917.43 = 891.95/x
  3. Step 3: Cross multiply
    1,390.10x = 1,917.43 × 891.95
  4. Step 4: Simplify right side
    1,390.10x = 1,710,251.69
  5. Step 5: Solve for x
    x = 1,710,251.69/1,390.10
  6. Step 6: Final answer
    x = 1,230.31

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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.