Answer:
1.46
Step-by-step explanation:
First find the the mean score before he made a 90.

Now add the score of 90 and calculate.

Subtract the two scores.

His mean test score increased by 1.46.
Answer/Step-by-step explanation:
1.
; 3
Let's solve for a.
(subtraction property of equality)

(division property of equality)


Therefore, 3 is a solution to 9 = 2a + 3
2.
; 7
(- × - = +)
(Subtraction property of equality)

(division property of equality)

Therefore, 7 is not a solution of 
3.
; 1
Therefore, 1 is a solution of
.
Answer: (12) ∠1 = 20° (13) ∠2 = 50° (14) ∠3 = 15° (15) UV = 80° (16) AB = 40° (17) ABC <em>or</em> 180° - CD (18) BC - 140° (19) ABC = 150°
<u>Step-by-step explanation:</u>
12)
(UV - ST) = ∠1
(80 - 40) = ∠1
(40) = ∠1
20 = ∠1
13)
(UV + ST) = ∠2
(70 + 30) = ∠2
(100) = ∠2
50 = ∠2
14)
(VB - BS) = ∠3
(60 - 30) = ∠3
(30) = ∠3
15 = ∠3
15)
(UV - ST) = ∠1
(UV - 20) = 30
UV - 20 = 60
UV = 80
16) ∠1 = arc AB
∠1 = 40
arc AB = 40
17) arc AB + arc BC = arc AC
= 180 = arc CD
18) ∠1 + ∠2 + ∠3 = 180
20 + ∠2 + 20 = 180
∠2 + 40 = 180
∠2 = 140
19) ∠1 + ∠ 2 = arc ABC
∠1 + ∠2 + ∠3 = 180
arc ABC + 30 = 180
arc ABC = 150
Answer:
D
Step-by-step explanation: