MATHEMATICS HIGH SCHOOL

A 20m ladder and a 15m ladder were leaned against a building. The bottom of the longer ladder was 7m farther from the building than the bottom of the shorter ladder, but both ladders reached the same distance up the building. Find this distance.6m

12m

10m

9m

Answers

Answer 1
Answer:

Answer:

The correct answer is: d=9m

Step-by-step explanation:

Ok, the ladders leaned against a building make two right triangles with same the same height, which we will call h. For the 20m ladder, its leg is (7+d) and for the 15m ladder, its leg is d, and the two hypotenuses are 20 and 15 respectively.

Then, using the Pythagorean Theorem we have:  

20m ladder:

20^2 = h^2 + (d+7)^2    (Eq. 1)

400 = h^2 + d^2 + 2*7*d + 7^2  (expanding the theorem)

400 = (h^2 + d^2) + 14*d + 49   (Eq. 2)

15m ladder:

 15^2 = h^2 + (d)^2         (Eq. 3)

Since h^2 + (d)^2 is equal to 15^2, we can substitute (2) into (3):

400 = (15^2) + 14*d + 49

400 = 225 + 14*d + 49

14*d = 400 - 225 - 49  (clearing the variable d)

14*d = 126

d = 9 m

And since we now know that d is equal to 9m. For the longer ladder is (d+7)=(9+7)=16m.

And, then the shorter ladder is 9m from the building and the longer ladder is 16m from the building

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What is the next fraction in this sequence? Simplify your answer. 3/4, 1/4, 1/12, 1/36

Answers

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John is playing a game of darts. The probability that he throws a dart into the center of the dart board (the Bull’s eye) is 1/10. The probability that he throws the dart into the 10-point ring is 3/10.What is the probability that he either hits a Bull’s eye or scores 10 points?
a. 1/3
b. 2/3
c. 3/5
d. 2/5
e. 1/4

Answers

The correct answer for the question that is being presented above is this one: "d. 2/5." John is playing a game of darts. The probability that he throws a dart into the center of the dart board (the Bull’s eye) is 1/10. The probability that he throws the dart into the 10-point ring is 3/10. The probability that he either hits a Bull's eye or scores 10 points is 2/5

Answer: The correct option is (d). (2)/(5).

Step-by-step explanation: Given that John is playing a game of darts. The probability that he throws a dart into the centre of the dart board (the Bull’s eye) is (1)/(10) and the probability that he throws the dart into the 10-point ring is (3)/(10).

We are to find the probability that he either hits a Bull’s eye or scores 10 points.

Let, 'A' and 'B' represents the events that John throws the dart into a Bull's eye and 10-point ring respectively.

Then, according to the given information, we have

P(A)=(1)/(10),~~P(B)=(3)/(10),~~~P(A\cup B)=?

Since John cannot throw the dart into the Bull's eye and 10 point ring together, both the events are independent of each other.

Therefore,

P(A\cap B)=0

From the theorems of probability, we have

P(A\cup B)=P(A)+P(B)-P(A\cap B)=(1)/(10)+(3)/(10)-0=(4)/(10)=(2)/(5).

Therefore, the probability that John either hits a Bull’s eye or scores 10 points is (2)/(5).

Thus, (d) is the correct option.
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