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Finding the Fourth Proportional to 1,278.45, 1,919.70 and 869.40

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Solution

The fourth proportional to 1,278.45, 1,919.70 and 869.40 is: 1,305.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.45 : 1,919.70 = 869.40 : x
  2. Step 2: Convert to fraction form
    1,278.45/1,919.70 = 869.40/x
  3. Step 3: Cross multiply
    1,278.45x = 1,919.70 × 869.40
  4. Step 4: Simplify right side
    1,278.45x = 1,668,987.18
  5. Step 5: Solve for x
    x = 1,668,987.18/1,278.45
  6. Step 6: Final answer
    x = 1,305.48

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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.