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Finding the Fourth Proportional to 2,139.74, 3,210 and 678.76

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Solution

The fourth proportional to 2,139.74, 3,210 and 678.76 is: 1,018.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,139.74 : 3,210 = 678.76 : x
  2. Step 2: Convert to fraction form
    2,139.74/3,210 = 678.76/x
  3. Step 3: Cross multiply
    2,139.74x = 3,210 × 678.76
  4. Step 4: Simplify right side
    2,139.74x = 2,178,819.60
  5. Step 5: Solve for x
    x = 2,178,819.60/2,139.74
  6. Step 6: Final answer
    x = 1,018.26

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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.