P=r x 2 x pi
= 3 x 2 x 3.14
= 6 x 3.14 = 18.84
Answer: 6,160,000 db
Step-by-step explanation:
The sound of a jet engine is 70,000 times louder than that of a lawn mower.
Since we know the sound of a lawnmower, we can multiply that by 70,000 to find the sound of a jet engine:
= Sound of lawnmower * 70,000
= 88 * 70,000
= 6,160,000 db
Answer:
The side of square A is 30 cm.
Step-by-step explanation:
Given that,
The dimensions of square A are three times the dimensions of square B.
The area of square A is 900 sq cm.
Side of square A = 3( side of square B)
Let the side of square B is b. So,
Side of square A, a = 3b
We know that, the area of square is side². So,
Side of square A, a = 3(10) = 30 cm
Hence, the side of square A is 30 cm.
When ever you have percentages, it should be helpful to bear in mind you can express them as multipliers. In this case, it will be helpful.
So, if we let:
a = test score
b = target score
then, using the information given:
a = 1.1b + 1
a = 1.15b - 3
and we get simultaneous equations.
'1.1' and '1.15' are the multipliers that I got using the percentages. Multiplying a value by 1.1 is the equivalent of increasing the value by 10%. If you multiplied it by 0.1 (which is the same as dividing by 10), you would get just 10% of the value.
Back to the simultaneous equations, we can just solve them now:
There are a number of ways to do this but I will use my preferred method:
Rearrange to express in terms of b:
a = 1.1b + 1
then b = (a - 1)/1.1
a = 1.15b - 3
then b = (a + 3)/1.15
Since they are both equal to b, they are of the same value so we can set them equal to each other and solve for a:
(a - 1)/1.1 = (a + 3)/1.15
1.15 * (a - 1) = 1.1 * (a + 3)
1.15a - 1.15 = 1.1a + 3.3
0.05a = 4.45
a = 89
