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Finding the Fourth Proportional to 1,386.60, 1,912.80 and 855.30

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Solution

The fourth proportional to 1,386.60, 1,912.80 and 855.30 is: 1,179.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.60 : 1,912.80 = 855.30 : x
  2. Step 2: Convert to fraction form
    1,386.60/1,912.80 = 855.30/x
  3. Step 3: Cross multiply
    1,386.60x = 1,912.80 × 855.30
  4. Step 4: Simplify right side
    1,386.60x = 1,636,017.84
  5. Step 5: Solve for x
    x = 1,636,017.84/1,386.60
  6. Step 6: Final answer
    x = 1,179.88

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.