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Finding the Fourth Proportional to 990.36, 1,485.53 and 259.92

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Solution

The fourth proportional to 990.36, 1,485.53 and 259.92 is: 389.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.36 : 1,485.53 = 259.92 : x
  2. Step 2: Convert to fraction form
    990.36/1,485.53 = 259.92/x
  3. Step 3: Cross multiply
    990.36x = 1,485.53 × 259.92
  4. Step 4: Simplify right side
    990.36x = 386,117.66
  5. Step 5: Solve for x
    x = 386,117.66/990.36
  6. Step 6: Final answer
    x = 389.88

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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.