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Finding the Fourth Proportional to 1,321.80, 1,985.40 and 1,275.90

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Solution

The fourth proportional to 1,321.80, 1,985.40 and 1,275.90 is: 1,916.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.80 : 1,985.40 = 1,275.90 : x
  2. Step 2: Convert to fraction form
    1,321.80/1,985.40 = 1,275.90/x
  3. Step 3: Cross multiply
    1,321.80x = 1,985.40 × 1,275.90
  4. Step 4: Simplify right side
    1,321.80x = 2,533,171.86
  5. Step 5: Solve for x
    x = 2,533,171.86/1,321.80
  6. Step 6: Final answer
    x = 1,916.46

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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.