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Finding the Fourth Proportional to 1,221.47, 1,685.64 and 661.95

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Solution

The fourth proportional to 1,221.47, 1,685.64 and 661.95 is: 913.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.47 : 1,685.64 = 661.95 : x
  2. Step 2: Convert to fraction form
    1,221.47/1,685.64 = 661.95/x
  3. Step 3: Cross multiply
    1,221.47x = 1,685.64 × 661.95
  4. Step 4: Simplify right side
    1,221.47x = 1,115,809.40
  5. Step 5: Solve for x
    x = 1,115,809.40/1,221.47
  6. Step 6: Final answer
    x = 913.50

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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.