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Finding the Fourth Proportional to 1,369.20, 2,054.40 and 638.40

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Solution

The fourth proportional to 1,369.20, 2,054.40 and 638.40 is: 957.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,369.20 : 2,054.40 = 638.40 : x
  2. Step 2: Convert to fraction form
    1,369.20/2,054.40 = 638.40/x
  3. Step 3: Cross multiply
    1,369.20x = 2,054.40 × 638.40
  4. Step 4: Simplify right side
    1,369.20x = 1,311,528.96
  5. Step 5: Solve for x
    x = 1,311,528.96/1,369.20
  6. Step 6: Final answer
    x = 957.88

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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.