Home / 976.80-1,347.36-780

Finding the Fourth Proportional to 976.80, 1,347.36 and 780

Calculator

Solution

The fourth proportional to 976.80, 1,347.36 and 780 is: 1,075.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    976.80 : 1,347.36 = 780 : x
  2. Step 2: Convert to fraction form
    976.80/1,347.36 = 780/x
  3. Step 3: Cross multiply
    976.80x = 1,347.36 × 780
  4. Step 4: Simplify right side
    976.80x = 1,050,940.80
  5. Step 5: Solve for x
    x = 1,050,940.80/976.80
  6. Step 6: Final answer
    x = 1,075.90

Related Problems

Find fourth proportional to 488.40, 673.68 and 390
Half scale
Find fourth proportional to 1,953.60, 2,694.72 and 1,560
Double scale
Find fourth proportional to 977.80, 1,348.74 and 781
Similar ratio
Find fourth proportional to 1,465.20, 2,021.04 and 1,170
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.