10 students averaged 80, so the sum of their scores was (10 x 80) = 800
20 students averaged 89, so the sum of their scores was (20 x 89) = 1,780
All together, the sum of all 30 scores was (800 + 1,780) = 2,580
30 students totaled 2,580, so their average was (2,580 / 30) = <em> 86</em> .
Answer
v=13
Step-by-step explanation:
110/9 = v
Round up.
21r < 7
Divide by 21
r < 7/21
Answer:


Step-by-step explanation:
To solve this question we're going to use trigonometric identities and good ol' Pythagoras theorem.
a) Firstly, sec(θ)=52. we're gonna convert this to cos(θ) using:

we can substitute the value of sec(θ) in this equation:

and solve for for cos(θ)

side note: just to confirm we can find the value of θ and verify that is indeed an acute angle by
b) since right triangle is mentioned in the question. We can use:

we know the value of cos(θ)=1\52. and by comparing the two. we can say that:
- length of the adjacent side = 1
- length of the hypotenuse = 52
we can find the third side using the Pythagoras theorem.




- length of the opposite side = √(2703) ≈ 51.9904
we can find the sin(θ) using this side:


and since 

Slot method
8 optionns n 1st slot
7 options in 2nd slot (since 1 is at 1st slot)
6 options in 3rd slot
5 options in 4th slot
8*7*6*5=1680 ways