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Finding the Fourth Proportional to 999.40, 1,378.66 and 820.20

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Solution

The fourth proportional to 999.40, 1,378.66 and 820.20 is: 1,131.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.40 : 1,378.66 = 820.20 : x
  2. Step 2: Convert to fraction form
    999.40/1,378.66 = 820.20/x
  3. Step 3: Cross multiply
    999.40x = 1,378.66 × 820.20
  4. Step 4: Simplify right side
    999.40x = 1,130,776.93
  5. Step 5: Solve for x
    x = 1,130,776.93/999.40
  6. Step 6: Final answer
    x = 1,131.46

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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.