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Finding the Fourth Proportional to 661.30, 912.36 and 399.40

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Solution

The fourth proportional to 661.30, 912.36 and 399.40 is: 551.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.30 : 912.36 = 399.40 : x
  2. Step 2: Convert to fraction form
    661.30/912.36 = 399.40/x
  3. Step 3: Cross multiply
    661.30x = 912.36 × 399.40
  4. Step 4: Simplify right side
    661.30x = 364,396.58
  5. Step 5: Solve for x
    x = 364,396.58/661.30
  6. Step 6: Final answer
    x = 551.03

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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.