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Finding the Fourth Proportional to 390.60, 538.56 and 316.80

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Solution

The fourth proportional to 390.60, 538.56 and 316.80 is: 436.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.60 : 538.56 = 316.80 : x
  2. Step 2: Convert to fraction form
    390.60/538.56 = 316.80/x
  3. Step 3: Cross multiply
    390.60x = 538.56 × 316.80
  4. Step 4: Simplify right side
    390.60x = 170,615.81
  5. Step 5: Solve for x
    x = 170,615.81/390.60
  6. Step 6: Final answer
    x = 436.80

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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.