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Finding the Fourth Proportional to 1,405.90, 1,939.67 and 909.17

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Solution

The fourth proportional to 1,405.90, 1,939.67 and 909.17 is: 1,254.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,405.90 : 1,939.67 = 909.17 : x
  2. Step 2: Convert to fraction form
    1,405.90/1,939.67 = 909.17/x
  3. Step 3: Cross multiply
    1,405.90x = 1,939.67 × 909.17
  4. Step 4: Simplify right side
    1,405.90x = 1,763,478.94
  5. Step 5: Solve for x
    x = 1,763,478.94/1,405.90
  6. Step 6: Final answer
    x = 1,254.34

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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.