Students poss a test if they score 50% or more
The marks of a large number of students were sampled and the mean and standard deviotion were calculated as 42%
and 8% respectively
Assuming this data is normally distributed, what percentage of students pass the test? in percentage

The decibel level of sound is 50 db greater on a busy street than in a quiet room where the intensity of sound is watt/m2. the level of sound in the quiet room is db, and the intensity of sound in the busy street is watt/m2. use the formula , where is the sound level in decibels, i is the intensity of sound, and is the smallest sound intensity that can be heard by the human ear (roughly equal to watts/m2).

Find the solution of this system of equation -7x+y=-20 9x-3y=36

Which number completes the system of linear inequalities represented by the graph? y> 2x – 2 and x + 4y 2 et 2 3 4