Represent these consecutive numbers (assuming that they are all integers):
x
x+1
x+2
x+3
x+4
x+5
and so on
x+8
x+9 is the tenth number. x+9 = 10, so x = 9.
Think of it this way: there are 10 consecutive numbers, and the last one is 10.
Working backwards, we get the sequence 10, 9, ... 3, 2, 1.
The sum of such an arith sequence is equal to the count of the numbers times the average of the first and last terms:
sum here = 10(1+10)/2 = 5(11) = 55 (answer)
Answer:
a) 12
b) 4
Step-by-step explanation:
:)
Answer:
50 Students
You can find the number of boys and girls by dividing the total, so there are a total of 20 boys and 30 girls in the choir of 50. The ratio 2 boys : 3 girls means we can divide the chorus into groups.
Answer: 88%
Step-by-step explanation:
Answer:
60 minutes for the larger hose to fill the swimming pool by itself
Step-by-step explanation:
It is given that,
Working together, it takes two different sized hoses 20 minutes to fill a small swimming pool.
takes 30 minutes for the larger hose to fill the swimming pool by itself
Let x be the efficiency to fill the swimming pool by larger hose
and y be the efficiency to fill the swimming pool by larger hose
<u>To find LCM of 20 and 30</u>
LCM (20, 30) = 60
<u>To find the efficiency </u>
Let x be the efficiency to fill the swimming pool by larger hose
and y be the efficiency to fill the swimming pool by larger hose
x = 60/30 =2
x + y = 60 /20 = 3
Therefore efficiency of y = (x + y) - x =3 - 2 = 1
so, time taken to fill the swimming pool by small hose = 60/1 = 60 minutes
