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Finding the Fourth Proportional to 990.55, 1,479.35 and 842.72

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Solution

The fourth proportional to 990.55, 1,479.35 and 842.72 is: 1,258.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.55 : 1,479.35 = 842.72 : x
  2. Step 2: Convert to fraction form
    990.55/1,479.35 = 842.72/x
  3. Step 3: Cross multiply
    990.55x = 1,479.35 × 842.72
  4. Step 4: Simplify right side
    990.55x = 1,246,677.83
  5. Step 5: Solve for x
    x = 1,246,677.83/990.55
  6. Step 6: Final answer
    x = 1,258.57

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.