Home / 1,418.40-2,128.80-639.60

Finding the Fourth Proportional to 1,418.40, 2,128.80 and 639.60

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Solution

The fourth proportional to 1,418.40, 2,128.80 and 639.60 is: 959.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,418.40 : 2,128.80 = 639.60 : x
  2. Step 2: Convert to fraction form
    1,418.40/2,128.80 = 639.60/x
  3. Step 3: Cross multiply
    1,418.40x = 2,128.80 × 639.60
  4. Step 4: Simplify right side
    1,418.40x = 1,361,580.48
  5. Step 5: Solve for x
    x = 1,361,580.48/1,418.40
  6. Step 6: Final answer
    x = 959.94

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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.