Home / 1,421.90-1,961.40-979.78

Finding the Fourth Proportional to 1,421.90, 1,961.40 and 979.78

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Solution

The fourth proportional to 1,421.90, 1,961.40 and 979.78 is: 1,351.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,421.90 : 1,961.40 = 979.78 : x
  2. Step 2: Convert to fraction form
    1,421.90/1,961.40 = 979.78/x
  3. Step 3: Cross multiply
    1,421.90x = 1,961.40 × 979.78
  4. Step 4: Simplify right side
    1,421.90x = 1,921,740.49
  5. Step 5: Solve for x
    x = 1,921,740.49/1,421.90
  6. Step 6: Final answer
    x = 1,351.53

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.