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Finding the Fourth Proportional to 1,221.50, 1,685.69 and 872.78

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Solution

The fourth proportional to 1,221.50, 1,685.69 and 872.78 is: 1,204.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.50 : 1,685.69 = 872.78 : x
  2. Step 2: Convert to fraction form
    1,221.50/1,685.69 = 872.78/x
  3. Step 3: Cross multiply
    1,221.50x = 1,685.69 × 872.78
  4. Step 4: Simplify right side
    1,221.50x = 1,471,236.52
  5. Step 5: Solve for x
    x = 1,471,236.52/1,221.50
  6. Step 6: Final answer
    x = 1,204.45

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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.