Home / 90.31-125.21-85.45

Finding the Fourth Proportional to 90.31, 125.21 and 85.45

Calculator

Solution

The fourth proportional to 90.31, 125.21 and 85.45 is: 118.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.31 : 125.21 = 85.45 : x
  2. Step 2: Convert to fraction form
    90.31/125.21 = 85.45/x
  3. Step 3: Cross multiply
    90.31x = 125.21 × 85.45
  4. Step 4: Simplify right side
    90.31x = 10,699.19
  5. Step 5: Solve for x
    x = 10,699.19/90.31
  6. Step 6: Final answer
    x = 118.47

Related Problems

Find fourth proportional to 45.16, 62.61 and 42.73
Half scale
Find fourth proportional to 180.62, 250.42 and 170.90
Double scale
Find fourth proportional to 91.31, 126.60 and 86.45
Similar ratio
Find fourth proportional to 135.47, 187.82 and 128.18
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.