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Finding the Fourth Proportional to 1,212.09, 1,672.68 and 688.15

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Solution

The fourth proportional to 1,212.09, 1,672.68 and 688.15 is: 949.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,212.09 : 1,672.68 = 688.15 : x
  2. Step 2: Convert to fraction form
    1,212.09/1,672.68 = 688.15/x
  3. Step 3: Cross multiply
    1,212.09x = 1,672.68 × 688.15
  4. Step 4: Simplify right side
    1,212.09x = 1,151,054.74
  5. Step 5: Solve for x
    x = 1,151,054.74/1,212.09
  6. Step 6: Final answer
    x = 949.64

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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.