HELP!!! use cross multiplication

Mathematics

2 answers:

Tresset [83]3 years ago

6 0

Let x be the number of square feet to be mowed
215 square feet take 22 minutes
x square feet take 12 minutes

$22x = 12 \times 215 \\ x = (12 \times 215) \div 22$

Georgia [21]3 years ago

6 0

29 square feet long I think

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andre [41]

Is it Im1,im2, 1m3??

7 0

3 years ago

Divide 1 hour in the ratio 1 : 9 : 10

olganol [36]

Answer:

3 minutes; 27 minutes; 30 minutes

Step-by-step explanation:

Let the common multiplier of the given ratios be x. So, the ratios 1: 9 : 10 will become x, 9x and 10x respectively.

Therefore,

$x + 9x + 10x = 1 \: hour \\ \\ 20x = 60 \: minutes \\ \\ x = \frac{60 \: minutes}{3} \\ \\ x = 3 \: minutes \\ \\ 9x = 9 \times 3 = 27 \: minutes \\ \\ 10x = 10 \times 3 = 30 \: minutes$

Thus, 1 hour in the ratio 1 : 9 : 10 can be divided as:

3 minutes; 27 minutes; 30 minutes

5 0

3 years ago

A ball is thrown in the air from a height of 3 m with an initial velocity of 12 m/s. To the nearest tenth of a second, how long

stepladder [879]

Answer: 1.4 seconds

<u>Step-by-step explanation:</u>

The equation is: h(t) = at² + v₀t + h₀ where

a is the acceleration (in this case it is gravity)
v₀ is the initial velocity
h₀ is the initial height

Given:

a = -9.81 (if it wasn't given in your textbook, you can look it up)
v₀ = 12
h₀ = 3

Since we are trying to find out when it lands on the ground, h(t) = 0

EQUATION: 0 = 9.81t² + 12t + 3

Use the quadratic equation to find the x-intercepts

a=-9.81, b=12, c=3

$x=\dfrac{-b \pm \sqrt{b^2-4ac}}{2a}\\\\\\x=\dfrac{-(12)\pm \sqrt{(12)^2-4(-9.81)(3)}}{2(-9.81)}\\\\\\x=\dfrac{-12\pm 16.2}{-19.62}\\\\\\x=\dfrac{-12+ 16.2}{-19.62}=-0.2\qquad x=\dfrac{-12- 16.2}{-19.62}=\large\boxed{1.4}\\$