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Finding the Fourth Proportional to 1,381.06, 1,905.63 and 821.51

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Solution

The fourth proportional to 1,381.06, 1,905.63 and 821.51 is: 1,133.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,381.06 : 1,905.63 = 821.51 : x
  2. Step 2: Convert to fraction form
    1,381.06/1,905.63 = 821.51/x
  3. Step 3: Cross multiply
    1,381.06x = 1,905.63 × 821.51
  4. Step 4: Simplify right side
    1,381.06x = 1,565,494.80
  5. Step 5: Solve for x
    x = 1,565,494.80/1,381.06
  6. Step 6: Final answer
    x = 1,133.55

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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.