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Finding the Fourth Proportional to 990.81, 1,366.71 and 636.61

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Solution

The fourth proportional to 990.81, 1,366.71 and 636.61 is: 878.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.81 : 1,366.71 = 636.61 : x
  2. Step 2: Convert to fraction form
    990.81/1,366.71 = 636.61/x
  3. Step 3: Cross multiply
    990.81x = 1,366.71 × 636.61
  4. Step 4: Simplify right side
    990.81x = 870,054.42
  5. Step 5: Solve for x
    x = 870,054.42/990.81
  6. Step 6: Final answer
    x = 878.13

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1.5x scale

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.