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Finding the Fourth Proportional to 1,221.81, 1,686.12 and 690.79

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Solution

The fourth proportional to 1,221.81, 1,686.12 and 690.79 is: 953.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.81 : 1,686.12 = 690.79 : x
  2. Step 2: Convert to fraction form
    1,221.81/1,686.12 = 690.79/x
  3. Step 3: Cross multiply
    1,221.81x = 1,686.12 × 690.79
  4. Step 4: Simplify right side
    1,221.81x = 1,164,754.83
  5. Step 5: Solve for x
    x = 1,164,754.83/1,221.81
  6. Step 6: Final answer
    x = 953.30

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1.5x scale

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.