Home / 105.21-157.48-85.91

Finding the Fourth Proportional to 105.21, 157.48 and 85.91

Calculator

Solution

The fourth proportional to 105.21, 157.48 and 85.91 is: 128.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.21 : 157.48 = 85.91 : x
  2. Step 2: Convert to fraction form
    105.21/157.48 = 85.91/x
  3. Step 3: Cross multiply
    105.21x = 157.48 × 85.91
  4. Step 4: Simplify right side
    105.21x = 13,528.10
  5. Step 5: Solve for x
    x = 13,528.10/105.21
  6. Step 6: Final answer
    x = 128.58

Related Problems

Find fourth proportional to 52.61, 78.74 and 42.95
Half scale
Find fourth proportional to 210.42, 314.96 and 171.81
Double scale
Find fourth proportional to 106.21, 158.97 and 86.91
Similar ratio
Find fourth proportional to 157.82, 236.22 and 128.86
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.