Answer:
P = 0.09r²
Step-by-step explanation:
Price, p is proportional to the square of its radius, r
P = k*r²
a mirror with radius 20cm has a price of £36
P = k * r²
36 = k * 20²
36 = k * 400
36 = 400k
k = 36/400
k = 0.09
Substitute the value of k into the equation:
P = k * r²
P = 0.09 * r²
P = 0.09r²
Answer:
1/6 = 0.1667 = 16.67%
Step-by-step explanation:
If there are 24 students in the class and 7 of them take neither courses, we have 17 students that take one or both courses.
To find the students that took both courses, we can use the formula:
N(Spanish or French) = N(Spanish) + N(French) - N(Spanish and French)
17 = 13 + 12 - N(Spanish and French)
N(Spanish and French) = 8
Then, the number of students that are taking only French is:
N(only French) = N(French) - N(Spanish and French)
N(only French) = 12 - 8 = 4
So the probability of chosing a student that took only French is:
P(only French) = N(only French) / N(total)
P(only French) = 4 / 24 = 1/6