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Finding the Fourth Proportional to 1,380.50, 1,905.49 and 821.36

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Solution

The fourth proportional to 1,380.50, 1,905.49 and 821.36 is: 1,133.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,380.50 : 1,905.49 = 821.36 : x
  2. Step 2: Convert to fraction form
    1,380.50/1,905.49 = 821.36/x
  3. Step 3: Cross multiply
    1,380.50x = 1,905.49 × 821.36
  4. Step 4: Simplify right side
    1,380.50x = 1,565,099.06
  5. Step 5: Solve for x
    x = 1,565,099.06/1,380.50
  6. Step 6: Final answer
    x = 1,133.72

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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.