Home / 1,120.80-1,681.20-939.90

Finding the Fourth Proportional to 1,120.80, 1,681.20 and 939.90

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Solution

The fourth proportional to 1,120.80, 1,681.20 and 939.90 is: 1,409.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,120.80 : 1,681.20 = 939.90 : x
  2. Step 2: Convert to fraction form
    1,120.80/1,681.20 = 939.90/x
  3. Step 3: Cross multiply
    1,120.80x = 1,681.20 × 939.90
  4. Step 4: Simplify right side
    1,120.80x = 1,580,159.88
  5. Step 5: Solve for x
    x = 1,580,159.88/1,120.80
  6. Step 6: Final answer
    x = 1,409.85

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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.