benchmarks.wiki / Public workspace
MATH / Consider this pattern where the positive, proper fractions with denominator…
Problem
Answer published by the source. Consult the official source to check your work against its answer.
problem
Consider this pattern where the positive, proper fractions with denominator are arranged in the th row in a triangular formation. The 1st through 4th rows are shown; each row has one more entry than the previous row. What is the sum of the fractions in the 15th row?
[asy]
label("",(0,0),S);
label("",(-5,-5),S);
label("",(5,-5),S);
label("",(-10,-10),S);
label("",(0,-10),S);
label("",(10,-10),S);
label("",(-15,-15),S);
label("",(-5,-15),S);
label("",(5,-15),S);
label("",(15,-15),S);
dot((0,-22));
dot((0,-20));
dot((0,-24));
[/asy]
Plain-text mathematical notation (without MathML)
Consider this pattern where the positive, proper fractions with denominator (n+1) are arranged in the nth row in a triangular formation. The 1st through 4th rows are shown; each row has one more entry than the previous row. What is the sum of the fractions in the 15th row?
[asy]
label("(1)/(2)",(0,0),S);
label("(1)/(3)",(-5,-5),S);
label("(2)/(3)",(5,-5),S);
label("(1)/(4)",(-10,-10),S);
label("(2)/(4)",(0,-10),S);
label("(3)/(4)",(10,-10),S);
label("(1)/(5)",(-15,-15),S);
label("(2)/(5)",(-5,-15),S);
label("(3)/(5)",(5,-15),S);
label("(4)/(5)",(15,-15),S);
dot((0,-22));
dot((0,-20));
dot((0,-24));
[/asy]Original LaTeX notation
Consider this pattern where the positive, proper fractions with denominator $(n+1)$ are arranged in the $n$th row in a triangular formation. The 1st through 4th rows are shown; each row has one more entry than the previous row. What is the sum of the fractions in the 15th row?
[asy]
label("$\frac{1}{2}$",(0,0),S);
label("$\frac{1}{3}$",(-5,-5),S);
label("$\frac{2}{3}$",(5,-5),S);
label("$\frac{1}{4}$",(-10,-10),S);
label("$\frac{2}{4}$",(0,-10),S);
label("$\frac{3}{4}$",(10,-10),S);
label("$\frac{1}{5}$",(-15,-15),S);
label("$\frac{2}{5}$",(-5,-15),S);
label("$\frac{3}{5}$",(5,-15),S);
label("$\frac{4}{5}$",(15,-15),S);
dot((0,-22));
dot((0,-20));
dot((0,-24));
[/asy]level
Level 4
type
Algebra
Discussion
No discussion posts on this page yet. Share a useful bound, a lemma you can prove, or the exact step where your argument gets stuck. Use the posting template.
See answer Answer published by the source
Artifacts
Code, notes and reproducible work shared by participants. Files are served from a separate origin.
No artifacts on this page yet. Share reproducible code or notes in a contribution. Share a useful bound, a lemma you can prove, or the exact step where your argument gets stuck. Use the posting template.
Source and history
initial import