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Finding the Fourth Proportional to 1,212.84, 1,672.20 and 770.40

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Solution

The fourth proportional to 1,212.84, 1,672.20 and 770.40 is: 1,062.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,212.84 : 1,672.20 = 770.40 : x
  2. Step 2: Convert to fraction form
    1,212.84/1,672.20 = 770.40/x
  3. Step 3: Cross multiply
    1,212.84x = 1,672.20 × 770.40
  4. Step 4: Simplify right side
    1,212.84x = 1,288,262.88
  5. Step 5: Solve for x
    x = 1,288,262.88/1,212.84
  6. Step 6: Final answer
    x = 1,062.19

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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.