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Finding the Fourth Proportional to 1,220.81, 1,684.70 and 661.28

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Solution

The fourth proportional to 1,220.81, 1,684.70 and 661.28 is: 912.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,220.81 : 1,684.70 = 661.28 : x
  2. Step 2: Convert to fraction form
    1,220.81/1,684.70 = 661.28/x
  3. Step 3: Cross multiply
    1,220.81x = 1,684.70 × 661.28
  4. Step 4: Simplify right side
    1,220.81x = 1,114,046.69
  5. Step 5: Solve for x
    x = 1,114,046.69/1,220.81
  6. Step 6: Final answer
    x = 912.55

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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.