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Finding the Fourth Proportional to 1,381.06, 1,905.35 and 821.55

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Solution

The fourth proportional to 1,381.06, 1,905.35 and 821.55 is: 1,133.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,381.06 : 1,905.35 = 821.55 : x
  2. Step 2: Convert to fraction form
    1,381.06/1,905.35 = 821.55/x
  3. Step 3: Cross multiply
    1,381.06x = 1,905.35 × 821.55
  4. Step 4: Simplify right side
    1,381.06x = 1,565,340.29
  5. Step 5: Solve for x
    x = 1,565,340.29/1,381.06
  6. Step 6: Final answer
    x = 1,133.43

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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.