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Finding the Fourth Proportional to 990.76, 1,485.15 and 644.32

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Solution

The fourth proportional to 990.76, 1,485.15 and 644.32 is: 965.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.76 : 1,485.15 = 644.32 : x
  2. Step 2: Convert to fraction form
    990.76/1,485.15 = 644.32/x
  3. Step 3: Cross multiply
    990.76x = 1,485.15 × 644.32
  4. Step 4: Simplify right side
    990.76x = 956,911.85
  5. Step 5: Solve for x
    x = 956,911.85/990.76
  6. Step 6: Final answer
    x = 965.84

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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.