Home / 1,119.80-1,680.20-389.90

Finding the Fourth Proportional to 1,119.80, 1,680.20 and 389.90

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Solution

The fourth proportional to 1,119.80, 1,680.20 and 389.90 is: 585.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,119.80 : 1,680.20 = 389.90 : x
  2. Step 2: Convert to fraction form
    1,119.80/1,680.20 = 389.90/x
  3. Step 3: Cross multiply
    1,119.80x = 1,680.20 × 389.90
  4. Step 4: Simplify right side
    1,119.80x = 655,109.98
  5. Step 5: Solve for x
    x = 655,109.98/1,119.80
  6. Step 6: Final answer
    x = 585.02

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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.