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Finding the Fourth Proportional to 651.99, 899.78 and 390

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Solution

The fourth proportional to 651.99, 899.78 and 390 is: 538.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    651.99 : 899.78 = 390 : x
  2. Step 2: Convert to fraction form
    651.99/899.78 = 390/x
  3. Step 3: Cross multiply
    651.99x = 899.78 × 390
  4. Step 4: Simplify right side
    651.99x = 350,912.25
  5. Step 5: Solve for x
    x = 350,912.25/651.99
  6. Step 6: Final answer
    x = 538.22

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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.