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Finding the Fourth Proportional to 1,211.70, 1,815.24 and 772.40

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Solution

The fourth proportional to 1,211.70, 1,815.24 and 772.40 is: 1,157.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.70 : 1,815.24 = 772.40 : x
  2. Step 2: Convert to fraction form
    1,211.70/1,815.24 = 772.40/x
  3. Step 3: Cross multiply
    1,211.70x = 1,815.24 × 772.40
  4. Step 4: Simplify right side
    1,211.70x = 1,402,091.38
  5. Step 5: Solve for x
    x = 1,402,091.38/1,211.70
  6. Step 6: Final answer
    x = 1,157.13

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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.