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Finding the Fourth Proportional to 998.87, 1,378.20 and 644.72

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Solution

The fourth proportional to 998.87, 1,378.20 and 644.72 is: 889.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.87 : 1,378.20 = 644.72 : x
  2. Step 2: Convert to fraction form
    998.87/1,378.20 = 644.72/x
  3. Step 3: Cross multiply
    998.87x = 1,378.20 × 644.72
  4. Step 4: Simplify right side
    998.87x = 888,548.45
  5. Step 5: Solve for x
    x = 888,548.45/998.87
  6. Step 6: Final answer
    x = 889.55

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Double scale
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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.