Home / 1,421.15-2,129.70-987.80

Finding the Fourth Proportional to 1,421.15, 2,129.70 and 987.80

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Solution

The fourth proportional to 1,421.15, 2,129.70 and 987.80 is: 1,480.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,421.15 : 2,129.70 = 987.80 : x
  2. Step 2: Convert to fraction form
    1,421.15/2,129.70 = 987.80/x
  3. Step 3: Cross multiply
    1,421.15x = 2,129.70 × 987.80
  4. Step 4: Simplify right side
    1,421.15x = 2,103,717.66
  5. Step 5: Solve for x
    x = 2,103,717.66/1,421.15
  6. Step 6: Final answer
    x = 1,480.29

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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.