15 out of 18 as a percentage is 83.33% (B)

A 15/18 is 83.33%, which is a B on the standard grading scale. That is a 3.0 GPA, and you got 3 wrong.

Next grade2 more → A17 out of 18 is 94.44%

With a 5-point curve88.33% → Bif your teacher adds 5 points

To pass (60%)Passed11 out of 18 is the passing line

What a 15/18 grade means

15 correct and 3 wrong on a 18-question test.
Each question is worth 5.56%, so every wrong answer costs 5.56 percentage points.
Any score from 15 to 16 out of 18 is a B.
2 more correct (17 out of 18, 94.44%) would make it an A.
It passes a 60% passing score, which needs 11 out of 18.

Divide the score by the total: 15 ÷ 18 = 0.8333.
Multiply by 100: 0.8333 × 100 = 83.33%.
Find 83.33% on the grading scale: A is 90% and up, B 80%, C 70% and D 60%, so it is a B.

Rounded to a whole number this is 83%, and the letter grade stays the same.

Scale	Cutoffs	Letter	GPA
Standard A–F	A 90, B 80, C 70, D 60	B	3.0
Plus and minus	A 93, A− 90, B+ 87, B 83, B− 80 …	B	3.0
7-point	A 93, B 85, C 77, D 70	C	2.0

Which scale applies depends on your school or teacher; the syllabus usually says. The grading scales guide compares them.

Every possible score out of 18, with 15 highlighted. Pick any score to see its page.

Correct	Wrong	Percentage	Grade
18	0	100%	A
17	1	94.4%	A
16	2	88.9%	B
15	3	83.3%	B
14	4	77.8%	C
13	5	72.2%	C
12	6	66.7%	D
11	7	61.1%	D
10	8	55.6%	F
9	9	50%	F
8	10	44.4%	F
7	11	38.9%	F
6	12	33.3%	F
5	13	27.8%	F
4	14	22.2%	F
3	15	16.7%	F
2	16	11.1%	F
1	17	5.6%	F
0	18	0%	F

Yes. It is a B, a solid grade above the C average. On a stricter 7-point scale it would be a C.

3.0 on a 4.0 scale, as a B.

With a half point, 15.5 out of 18 is 86.11%: a B on the standard scale and a B with plus and minus grades.

7 at most with a 60% passing score: you need 11 out of 18. With a 70% passing score you need 13 out of 18.