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Finding the Fourth Proportional to 1,220.74, 1,684.62 and 661.21

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Solution

The fourth proportional to 1,220.74, 1,684.62 and 661.21 is: 912.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,220.74 : 1,684.62 = 661.21 : x
  2. Step 2: Convert to fraction form
    1,220.74/1,684.62 = 661.21/x
  3. Step 3: Cross multiply
    1,220.74x = 1,684.62 × 661.21
  4. Step 4: Simplify right side
    1,220.74x = 1,113,887.59
  5. Step 5: Solve for x
    x = 1,113,887.59/1,220.74
  6. Step 6: Final answer
    x = 912.47

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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.