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Finding the Fourth Proportional to 990.76, 1,366.32 and 640.84

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Solution

The fourth proportional to 990.76, 1,366.32 and 640.84 is: 883.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.76 : 1,366.32 = 640.84 : x
  2. Step 2: Convert to fraction form
    990.76/1,366.32 = 640.84/x
  3. Step 3: Cross multiply
    990.76x = 1,366.32 × 640.84
  4. Step 4: Simplify right side
    990.76x = 875,592.51
  5. Step 5: Solve for x
    x = 875,592.51/990.76
  6. Step 6: Final answer
    x = 883.76

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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.