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Finding the Fourth Proportional to 1,278.80, 1,918.20 and 868.40

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Solution

The fourth proportional to 1,278.80, 1,918.20 and 868.40 is: 1,302.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.80 : 1,918.20 = 868.40 : x
  2. Step 2: Convert to fraction form
    1,278.80/1,918.20 = 868.40/x
  3. Step 3: Cross multiply
    1,278.80x = 1,918.20 × 868.40
  4. Step 4: Simplify right side
    1,278.80x = 1,665,764.88
  5. Step 5: Solve for x
    x = 1,665,764.88/1,278.80
  6. Step 6: Final answer
    x = 1,302.60

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1.5x scale

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.