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Finding the Fourth Proportional to 869.80, 1,304.70 and 780.20

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Solution

The fourth proportional to 869.80, 1,304.70 and 780.20 is: 1,170.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.80 : 1,304.70 = 780.20 : x
  2. Step 2: Convert to fraction form
    869.80/1,304.70 = 780.20/x
  3. Step 3: Cross multiply
    869.80x = 1,304.70 × 780.20
  4. Step 4: Simplify right side
    869.80x = 1,017,926.94
  5. Step 5: Solve for x
    x = 1,017,926.94/869.80
  6. Step 6: Final answer
    x = 1,170.30

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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.