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Finding the Fourth Proportional to 2,720.60, 4,080.90 and 989

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Solution

The fourth proportional to 2,720.60, 4,080.90 and 989 is: 1,483.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,720.60 : 4,080.90 = 989 : x
  2. Step 2: Convert to fraction form
    2,720.60/4,080.90 = 989/x
  3. Step 3: Cross multiply
    2,720.60x = 4,080.90 × 989
  4. Step 4: Simplify right side
    2,720.60x = 4,036,010.10
  5. Step 5: Solve for x
    x = 4,036,010.10/2,720.60
  6. Step 6: Final answer
    x = 1,483.50

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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.