Solve the equation for
t
t
by finding
a
a
,
b
b
, and
c
c
of the quadratic then applying the quadratic formula.
t
=
10
−
h
+
√
h
2
−
20
h
+
160
10
t
=
10
-
h
+
h
2
-
20
h
+
160
10
t
=
10
−
h
−
√
h
2
−
20
h
+
160
10
75p is the correct answer because 1 lemon is 15p
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
A = -16 b = 0 c = 541
Use the quadratic formula which is
x = [-b +- sq root (b^2 -4*a*c)] / 2*a
x = [-0 +-sq root (0 -4*-16*541)] / 2 * -16
x = + - sq root (0 -4*-16*541) / -32
x = + - sq root (34,624) / -32
x = + - 186.075 / -32
x1 = 186.075 / -32 =
<span>
<span>
<span>
-5.81484375
</span>
</span>
</span>
x2 = -186.075 / -32 =
<span>
<span>
<span>
5.81484375
</span>
</span>
</span>
