Home / 207.78-311.67-86.15

Finding the Fourth Proportional to 207.78, 311.67 and 86.15

Calculator

Solution

The fourth proportional to 207.78, 311.67 and 86.15 is: 129.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.78 : 311.67 = 86.15 : x
  2. Step 2: Convert to fraction form
    207.78/311.67 = 86.15/x
  3. Step 3: Cross multiply
    207.78x = 311.67 × 86.15
  4. Step 4: Simplify right side
    207.78x = 26,848.81
  5. Step 5: Solve for x
    x = 26,848.81/207.78
  6. Step 6: Final answer
    x = 129.22

Related Problems

Find fourth proportional to 103.89, 155.84 and 43.07
Half scale
Find fourth proportional to 415.56, 623.34 and 172.29
Double scale
Find fourth proportional to 208.78, 313.17 and 87.15
Similar ratio
Find fourth proportional to 311.67, 467.51 and 129.22
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.