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Finding the Fourth Proportional to 985.47, 1,478.21 and 255

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Solution

The fourth proportional to 985.47, 1,478.21 and 255 is: 382.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.47 : 1,478.21 = 255 : x
  2. Step 2: Convert to fraction form
    985.47/1,478.21 = 255/x
  3. Step 3: Cross multiply
    985.47x = 1,478.21 × 255
  4. Step 4: Simplify right side
    985.47x = 376,943.55
  5. Step 5: Solve for x
    x = 376,943.55/985.47
  6. Step 6: Final answer
    x = 382.50

Related Problems

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Double scale
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Similar ratio
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1.5x scale

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.