Home / 85.07-128.03-76.68

Finding the Fourth Proportional to 85.07, 128.03 and 76.68

Calculator

Solution

The fourth proportional to 85.07, 128.03 and 76.68 is: 115.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.07 : 128.03 = 76.68 : x
  2. Step 2: Convert to fraction form
    85.07/128.03 = 76.68/x
  3. Step 3: Cross multiply
    85.07x = 128.03 × 76.68
  4. Step 4: Simplify right side
    85.07x = 9,817.39
  5. Step 5: Solve for x
    x = 9,817.39/85.07
  6. Step 6: Final answer
    x = 115.41

Related Problems

Find fourth proportional to 42.53, 64.02 and 38.34
Half scale
Find fourth proportional to 170.13, 256.06 and 153.36
Double scale
Find fourth proportional to 86.07, 129.54 and 77.68
Similar ratio
Find fourth proportional to 127.60, 192.05 and 115.02
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.