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Finding the Fourth Proportional to 1,386.21, 1,912.92 and 765.21

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Solution

The fourth proportional to 1,386.21, 1,912.92 and 765.21 is: 1,055.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.21 : 1,912.92 = 765.21 : x
  2. Step 2: Convert to fraction form
    1,386.21/1,912.92 = 765.21/x
  3. Step 3: Cross multiply
    1,386.21x = 1,912.92 × 765.21
  4. Step 4: Simplify right side
    1,386.21x = 1,463,785.51
  5. Step 5: Solve for x
    x = 1,463,785.51/1,386.21
  6. Step 6: Final answer
    x = 1,055.96

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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.