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Finding the Fourth Proportional to 1,221.06, 1,685.06 and 661.53

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Solution

The fourth proportional to 1,221.06, 1,685.06 and 661.53 is: 912.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.06 : 1,685.06 = 661.53 : x
  2. Step 2: Convert to fraction form
    1,221.06/1,685.06 = 661.53/x
  3. Step 3: Cross multiply
    1,221.06x = 1,685.06 × 661.53
  4. Step 4: Simplify right side
    1,221.06x = 1,114,717.74
  5. Step 5: Solve for x
    x = 1,114,717.74/1,221.06
  6. Step 6: Final answer
    x = 912.91

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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.