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Finding the Fourth Proportional to 990.30, 1,484.37 and 643.88

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Solution

The fourth proportional to 990.30, 1,484.37 and 643.88 is: 965.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.30 : 1,484.37 = 643.88 : x
  2. Step 2: Convert to fraction form
    990.30/1,484.37 = 643.88/x
  3. Step 3: Cross multiply
    990.30x = 1,484.37 × 643.88
  4. Step 4: Simplify right side
    990.30x = 955,756.16
  5. Step 5: Solve for x
    x = 955,756.16/990.30
  6. Step 6: Final answer
    x = 965.12

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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.