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Finding the Fourth Proportional to 919.47, 1,378.18 and 399.30

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Solution

The fourth proportional to 919.47, 1,378.18 and 399.30 is: 598.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.47 : 1,378.18 = 399.30 : x
  2. Step 2: Convert to fraction form
    919.47/1,378.18 = 399.30/x
  3. Step 3: Cross multiply
    919.47x = 1,378.18 × 399.30
  4. Step 4: Simplify right side
    919.47x = 550,307.27
  5. Step 5: Solve for x
    x = 550,307.27/919.47
  6. Step 6: Final answer
    x = 598.50

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Double scale
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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.