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Finding the Fourth Proportional to 1,381.41, 1,905.81 and 821.76

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Solution

The fourth proportional to 1,381.41, 1,905.81 and 821.76 is: 1,133.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,381.41 : 1,905.81 = 821.76 : x
  2. Step 2: Convert to fraction form
    1,381.41/1,905.81 = 821.76/x
  3. Step 3: Cross multiply
    1,381.41x = 1,905.81 × 821.76
  4. Step 4: Simplify right side
    1,381.41x = 1,566,118.43
  5. Step 5: Solve for x
    x = 1,566,118.43/1,381.41
  6. Step 6: Final answer
    x = 1,133.71

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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.