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Finding the Fourth Proportional to 1,442.28, 1,990.62 and 821.28

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Solution

The fourth proportional to 1,442.28, 1,990.62 and 821.28 is: 1,133.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,442.28 : 1,990.62 = 821.28 : x
  2. Step 2: Convert to fraction form
    1,442.28/1,990.62 = 821.28/x
  3. Step 3: Cross multiply
    1,442.28x = 1,990.62 × 821.28
  4. Step 4: Simplify right side
    1,442.28x = 1,634,856.39
  5. Step 5: Solve for x
    x = 1,634,856.39/1,442.28
  6. Step 6: Final answer
    x = 1,133.52

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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.