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Finding the Fourth Proportional to 1,386.80, 2,080.20 and 838.70

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Solution

The fourth proportional to 1,386.80, 2,080.20 and 838.70 is: 1,258.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.80 : 2,080.20 = 838.70 : x
  2. Step 2: Convert to fraction form
    1,386.80/2,080.20 = 838.70/x
  3. Step 3: Cross multiply
    1,386.80x = 2,080.20 × 838.70
  4. Step 4: Simplify right side
    1,386.80x = 1,744,663.74
  5. Step 5: Solve for x
    x = 1,744,663.74/1,386.80
  6. Step 6: Final answer
    x = 1,258.05

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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.