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Finding the Fourth Proportional to 1,389.68, 2,087.84 and 812.96

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Solution

The fourth proportional to 1,389.68, 2,087.84 and 812.96 is: 1,221.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.68 : 2,087.84 = 812.96 : x
  2. Step 2: Convert to fraction form
    1,389.68/2,087.84 = 812.96/x
  3. Step 3: Cross multiply
    1,389.68x = 2,087.84 × 812.96
  4. Step 4: Simplify right side
    1,389.68x = 1,697,330.41
  5. Step 5: Solve for x
    x = 1,697,330.41/1,389.68
  6. Step 6: Final answer
    x = 1,221.38

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.