B1. a) From the histogram, we count the girls and boys of all ages: $4+6+4+4+8+6+10+$ $12+6+8=68$ participants.

b) In the age group of 14-year-olds, there are more boys than girls.

c) Out of all 68 participants, 36 are girls, which is $53 \%$.

d) There are 32 boys and 36 girls. The ratio of the number of boys to girls is $32: 36=8: 9$.

e) On average, girls are $\frac{6 \cdot 12+4 \cdot 13+6 \cdot 14+12 \cdot 15+8 \cdot 16}{36}=14.3$ years old.

## Scoring: Total: 5 points

a) The total number of participants in the course is 68.

b) There are more boys than girls in the age group of 14 years.

c) Girls represent $53 \%$ of all participants.

d) The ratio "number of girls : number of boys" is $36: 32=9: 8$

e) On average, girls are 14.3 years old.

(If the contestant did not consider rounding, they do not receive any points.)
B1. A dance course is attended by students aged 12 to 16. The age composition is shown in the diagram.

![](https://cdn.mathpix.com/cropped/2024_06_07_e0eaf7053b4419cdf2d7g-4.jpg?height=736&width=945&top_left_y=1094&top_left_x=453)

a) How many participants are there in the dance course?

b) In which age group are there more boys than girls?

c) What percentage of all participants are girls?

d) What is the ratio of the number of boys to the number of girls?

e) What is the average age of the girls? Round the result to one decimal place.