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Finding the Fourth Proportional to 645.69, 891.09 and 380.15

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Solution

The fourth proportional to 645.69, 891.09 and 380.15 is: 524.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.69 : 891.09 = 380.15 : x
  2. Step 2: Convert to fraction form
    645.69/891.09 = 380.15/x
  3. Step 3: Cross multiply
    645.69x = 891.09 × 380.15
  4. Step 4: Simplify right side
    645.69x = 338,741.51
  5. Step 5: Solve for x
    x = 338,741.51/645.69
  6. Step 6: Final answer
    x = 524.62

Related Problems

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Half scale
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Double scale
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1.5x scale

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.