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Finding the Fourth Proportional to 1,221.20, 1,685.20 and 697.20

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Solution

The fourth proportional to 1,221.20, 1,685.20 and 697.20 is: 962.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.20 : 1,685.20 = 697.20 : x
  2. Step 2: Convert to fraction form
    1,221.20/1,685.20 = 697.20/x
  3. Step 3: Cross multiply
    1,221.20x = 1,685.20 × 697.20
  4. Step 4: Simplify right side
    1,221.20x = 1,174,921.44
  5. Step 5: Solve for x
    x = 1,174,921.44/1,221.20
  6. Step 6: Final answer
    x = 962.10

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Double scale
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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.