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Finding the Fourth Proportional to 1,129.78, 1,555.63 and 989.11

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Solution

The fourth proportional to 1,129.78, 1,555.63 and 989.11 is: 1,361.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,129.78 : 1,555.63 = 989.11 : x
  2. Step 2: Convert to fraction form
    1,129.78/1,555.63 = 989.11/x
  3. Step 3: Cross multiply
    1,129.78x = 1,555.63 × 989.11
  4. Step 4: Simplify right side
    1,129.78x = 1,538,689.19
  5. Step 5: Solve for x
    x = 1,538,689.19/1,129.78
  6. Step 6: Final answer
    x = 1,361.94

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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.