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Finding the Fourth Proportional to 1,211.80, 1,817.70 and 920.20

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Solution

The fourth proportional to 1,211.80, 1,817.70 and 920.20 is: 1,380.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.80 : 1,817.70 = 920.20 : x
  2. Step 2: Convert to fraction form
    1,211.80/1,817.70 = 920.20/x
  3. Step 3: Cross multiply
    1,211.80x = 1,817.70 × 920.20
  4. Step 4: Simplify right side
    1,211.80x = 1,672,647.54
  5. Step 5: Solve for x
    x = 1,672,647.54/1,211.80
  6. Step 6: Final answer
    x = 1,380.30

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.