Answer:
43
Step-by-step explanation:
Let's call this number x. The word sum means addition, so we can write x + 21 = 64. When we subtract 21 from both sides, we get x = 43. Hope this helps!
The probability tests to detect the presence of hepatitis B:
P (presence)= 0.97 (true) 0.03 (false)
P (absence)= 0.99 (true) 0.01 (false)
P(infected)=0.0055
P(not infected)= 0.9945
To have an incorrect result:
P[infected and false from P(presence)] + P[not infected and false from P(absence)]
=0.0055*0.03+0.9945*0.01= 0.01011
The answer is<span> 0.01011 </span>
Answer:
B.
Step-by-step explanation:
x < 2 means all numbers less than 2. that is an open dot on 2 and shading to the left.
x >= -8 means -8 and all numbers greater than -8. that is a closed dot on -8 and shading to the right.
Answer: B.
11
(9, 18, 27, 36, 45, 54, 63, 72, 81, 90 and 99)
Those numbers divisible by 9 are the multiple of 9; thus need to know how many multiples of 9 there are between 1 and 100:
100 ÷ 9 = 11 r 1 ÷ last multiple of 9 is 11 × 9 (= 99)
→ There are 11 - 1 + 1 = 11 numbers between 1 and 100 which are divisible by 9.
(They are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99.)

Explanation:
Since we have given that
Speed at which Eugene walked all the way to school = 3 mph
After realizing that she forgot her math book, she ran back
Speed at which Eugene walked back to her house = 7 mph
Let the distance between her house and her school be x
According to question,

Hence,
