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Finding the Fourth Proportional to 1,278.66, 1,916.62 and 661.74

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Solution

The fourth proportional to 1,278.66, 1,916.62 and 661.74 is: 991.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.66 : 1,916.62 = 661.74 : x
  2. Step 2: Convert to fraction form
    1,278.66/1,916.62 = 661.74/x
  3. Step 3: Cross multiply
    1,278.66x = 1,916.62 × 661.74
  4. Step 4: Simplify right side
    1,278.66x = 1,268,304.12
  5. Step 5: Solve for x
    x = 1,268,304.12/1,278.66
  6. Step 6: Final answer
    x = 991.90

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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.