Home / 86.51-128.87-84.12

Finding the Fourth Proportional to 86.51, 128.87 and 84.12

Calculator

Solution

The fourth proportional to 86.51, 128.87 and 84.12 is: 125.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.51 : 128.87 = 84.12 : x
  2. Step 2: Convert to fraction form
    86.51/128.87 = 84.12/x
  3. Step 3: Cross multiply
    86.51x = 128.87 × 84.12
  4. Step 4: Simplify right side
    86.51x = 10,840.12
  5. Step 5: Solve for x
    x = 10,840.12/86.51
  6. Step 6: Final answer
    x = 125.31

Related Problems

Find fourth proportional to 43.25, 64.43 and 42.06
Half scale
Find fourth proportional to 173.01, 257.73 and 168.24
Double scale
Find fourth proportional to 87.51, 130.35 and 85.12
Similar ratio
Find fourth proportional to 129.76, 193.30 and 126.18
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.