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Finding the Fourth Proportional to 1,221.68, 1,686.02 and 690.66

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Solution

The fourth proportional to 1,221.68, 1,686.02 and 690.66 is: 953.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.68 : 1,686.02 = 690.66 : x
  2. Step 2: Convert to fraction form
    1,221.68/1,686.02 = 690.66/x
  3. Step 3: Cross multiply
    1,221.68x = 1,686.02 × 690.66
  4. Step 4: Simplify right side
    1,221.68x = 1,164,463.12
  5. Step 5: Solve for x
    x = 1,164,463.12/1,221.68
  6. Step 6: Final answer
    x = 953.16

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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.