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Finding the Fourth Proportional to 1,315.90, 1,973.51 and 391.21

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Solution

The fourth proportional to 1,315.90, 1,973.51 and 391.21 is: 586.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,315.90 : 1,973.51 = 391.21 : x
  2. Step 2: Convert to fraction form
    1,315.90/1,973.51 = 391.21/x
  3. Step 3: Cross multiply
    1,315.90x = 1,973.51 × 391.21
  4. Step 4: Simplify right side
    1,315.90x = 772,049.96
  5. Step 5: Solve for x
    x = 772,049.96/1,315.90
  6. Step 6: Final answer
    x = 586.71

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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.