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Finding the Fourth Proportional to 1,390.45, 1,919.15 and 918.43

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Solution

The fourth proportional to 1,390.45, 1,919.15 and 918.43 is: 1,267.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.45 : 1,919.15 = 918.43 : x
  2. Step 2: Convert to fraction form
    1,390.45/1,919.15 = 918.43/x
  3. Step 3: Cross multiply
    1,390.45x = 1,919.15 × 918.43
  4. Step 4: Simplify right side
    1,390.45x = 1,762,600.34
  5. Step 5: Solve for x
    x = 1,762,600.34/1,390.45
  6. Step 6: Final answer
    x = 1,267.65

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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.