Answer:
1287
Step-by-step explanation:
Number of people in elevator , n = 8
Number of floors, r = 6
Since they all look alike, arrangement doesn't matter, the we use combination :
(n+r-1 r - 1) = (8+6-1 C 6-1) = 13C5
Recall:
nCr = n! / (n-r)!r!
13C5 = 13! / (13-5)!5!
13C5 = 13*12*11*10*9 / 5*4*3*2*1
= 1287
Answer:
a = 30
b = 40
C
Step-by-step explanation:
This requires that you use a proportion.
a / (a + 15) = 40 / 60
The small triangle's sides are in proportion to the large triangles sides.
Reduce the right. Divide top and bottom by 20
a/(a + 15) = 40/20 // 60/20
a/(a + 15) = 2/3
Cross multiply
3a = 2(a + 15) Remove the brackets on the right.
3a = 2a + 30
Subtract 2a from both sides
3a-2a = 30
a = 30
Find B
b is done exactly the same way.
b/(b+20) = 2/3
3b = 2b + 40
3b - 2b = 40
b = 40
Answer:
the cat weighs 21 pounds.
the dog weighs 43 pounds
Step-by-step explanation:
dog = 3x-20 = x + 22
cat = x
3x-20 = x+22
3x = x+42 (add 20 to both sides)
2x = 42 (subtract x from both sides)
x = 21
1/2, because 3/10 + 1/5 = 5/10. that means that the other part of 1 is 5/10 or 1/2
It is 9 because you have a 30,60,90 triangle, and then you can use pythagorean theorem.
