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Finding the Fourth Proportional to 1,209.78, 1,669.48 and 678.67

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Solution

The fourth proportional to 1,209.78, 1,669.48 and 678.67 is: 936.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.78 : 1,669.48 = 678.67 : x
  2. Step 2: Convert to fraction form
    1,209.78/1,669.48 = 678.67/x
  3. Step 3: Cross multiply
    1,209.78x = 1,669.48 × 678.67
  4. Step 4: Simplify right side
    1,209.78x = 1,133,014.25
  5. Step 5: Solve for x
    x = 1,133,014.25/1,209.78
  6. Step 6: Final answer
    x = 936.55

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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.