Mean:
E[Y] = E[3X₁ + X₂]
E[Y] = 3 E[X₁] + E[X₂]
E[Y] = 3µ + µ
E[Y] = 4µ
Variance:
Var[Y] = Var[3X₁ + X₂]
Var[Y] = 3² Var[X₁] + 2 Covar[X₁, X₂] + 1² Var[X₂]
(the covariance is 0 since X₁ and X₂ are independent)
Var[Y] = 9 Var[X₁] + Var[X₂]
Var[Y] = 9σ² + σ²
Var[Y] = 10σ²
Hello!
I will make approximations below to the nearest whole number
A. 2√32≈11
B. 5+√18≈9
C. √24≈5
D. √52-3≈4
E. 3√14≈11
F. √20+√26≈10
Based off of what we see here our even numbers are 
and 
.
I hope this helps!
Answer:
Streamers are $2.50 each
Balloons are $1.50 each
Step-by-step explanation:
Make a system of equations
3s + 15b = 30
2s + 4b = 11
Solve by elimination: multiply the top equation by 2 and the bottom equation by -3.
6s + 30b = 60
-6s -12b = -33
18b = 27
b = 1.5
Plug in 1.5 as b to find s
3s + 15(1.5) = 30
3s +22.5 = 30
3s = 7.5
s = 2.5
The streamers are $2.50 and the balloons are $1.50
