The mean age of a group of students is 15 years. When the...
The mean age of a group of students is 15 years. When the age of a teacher, 45 years old, is added to the age of the students, the mean of their ages becomes 18 years. Find the number of the students in the group
9
7
42
15
Correct answer is A
Let the number of students = x
Total age of the students = 15x
Total age including age of the teacher = 15x + 45
Mean of their ages; (15x + 45)/(x + 1) = 18
15x + 45 = 18(x + 1)
15x + 45 = 18x + 18
18x - 15x = 45 - 18
3x = 27
x = 9
PQRS is a rhombus. If PR2 + QS2 = kPQ2, determine k....
Make r subject of the formula given that xr+a=ar ...
Marks 3 4 5 6 7 8 Frequency 5 y - 1 y ...
The sum of 378 and 113 is less than the difference between 18...
Simplify f12g2h12 ÷ f52goh73...
Find, correct to three significant figures, the value of √41830....
Express 1975 correct to 2 significant figures ...
If a = 2, b = -2 and c = -12, evaluate (ab2 - bc2)(a2c - abc)...