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Finding the Fourth Proportional to 1,221.13, 1,685.16 and 661.60

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Solution

The fourth proportional to 1,221.13, 1,685.16 and 661.60 is: 913.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.13 : 1,685.16 = 661.60 : x
  2. Step 2: Convert to fraction form
    1,221.13/1,685.16 = 661.60/x
  3. Step 3: Cross multiply
    1,221.13x = 1,685.16 × 661.60
  4. Step 4: Simplify right side
    1,221.13x = 1,114,895.16
  5. Step 5: Solve for x
    x = 1,114,895.16/1,221.13
  6. Step 6: Final answer
    x = 913.00

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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.