Answer:
4 and 5
Step-by-step explanation:
Let the numbers be x and y
If their sum is 9, hence;
x + y = 9 ....1
When reversed
10y+x = 2(10x+y)
10y+x = 20x + 2y
10y - 2y = 20x - x
8y = 19x
y = 10x/8 ...2
Substitute equation 2 into 1;
From 1;
x+y = 9
x +(10x/8) = 9
18x/8 = 9
18x = 72
x = 72/18
x = 4
Since x+y =9
y = 9-x
y =9-4
y = 5
Hence the numbers are 4 and 5
C is the answer to your problem have a good day
Answer:
105
For the 4 triangular faces, find the area with 1/2 × base × height = 1/2 × 5 × 8 = 20
4 triangles -> 20 × 4 = 80
The area of the square base is 25
80 + 25 - 105 
Answer:
Example:
A bag contains 3 black balls and 5 white balls. Paul picks a ball at random from the bag and replaces it back in the bag. He mixes the balls in the bag and then picks another ball at random from the bag.
a) Construct a probability tree of the problem.
b) Calculate the probability that Paul picks:
i) two black balls
ii) a black ball in his second draw
Solution:
tree diagram
a) Check that the probabilities in the last column add up to 1.
b) i) To find the probability of getting two black balls, first locate the B branch and then follow the second B branch. Since these are independent events we can multiply the probability of each branch.
ii) There are two outcomes where the second ball can be black.
Either (B, B) or (W, B)
From the probability tree diagram, we get:
P(second ball black)
= P(B, B) or P(W, B)
= P(B, B) + P(W, B)
