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Finding the Fourth Proportional to 935.85, 1,290.78 and 687.09

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Solution

The fourth proportional to 935.85, 1,290.78 and 687.09 is: 947.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    935.85 : 1,290.78 = 687.09 : x
  2. Step 2: Convert to fraction form
    935.85/1,290.78 = 687.09/x
  3. Step 3: Cross multiply
    935.85x = 1,290.78 × 687.09
  4. Step 4: Simplify right side
    935.85x = 886,878.59
  5. Step 5: Solve for x
    x = 886,878.59/935.85
  6. Step 6: Final answer
    x = 947.67

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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.