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Finding the Fourth Proportional to 1,212, 1,672.75 and 688.20

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Solution

The fourth proportional to 1,212, 1,672.75 and 688.20 is: 949.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,212 : 1,672.75 = 688.20 : x
  2. Step 2: Convert to fraction form
    1,212/1,672.75 = 688.20/x
  3. Step 3: Cross multiply
    1,212x = 1,672.75 × 688.20
  4. Step 4: Simplify right side
    1,212x = 1,151,186.55
  5. Step 5: Solve for x
    x = 1,151,186.55/1,212
  6. Step 6: Final answer
    x = 949.82

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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.