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2 years ago

7

Sally can paint a room in 7 hours while it takes Steve 6 hours to paint the same room. How long would it take them to paint the

room if they worked together?

2 answers:

Kipish [7]2 years ago

6 0

I would say about 6.25 hours

attashe74 [19]2 years ago

3 0

I think about 2.5 hours

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Can someone help me with this

Dafna1 [17]

Answer:

18.18 /// 17.9982

Step-by-step explanation:

Multiplying by 100 means moving up the other number by two digits,

soo 100x (or 100(0.1818) is now 18.18

For the next one:

0. 1818

x 99

---------------

1.6362

16.3620

-------------

17.9982

I have no idea about that fraction part

5 0

2 years ago

Read 2 more answers

Which answer is the approximate standard deviation of the data set?

Anna35 [415]

Answer:

3.4

Step-by-step explanation:

Standard deviation of a population is defined as:

σ² = ∑(xᵢ − μ)² / n

The standard deviation of a sample is defined as:

s² = ∑(xᵢ − x)² / (n - 1)

It's not clear which one we have, so let's calculate both.

First, we must find the mean.

μ = (5+12+15+10+12+6+8+8) / 8

μ = 9.5

Now we find the squares of the differences:

(5-9.5)² + (12-9.5)² + (15-9.5)² + (10-9.5)² + (12-9.5)² + (6-9.5)² + (8-9.5)² + (8-9.5)²

= 80

Divide by n:

σ² = 80 / 8

σ² = 10

And take the square root:

σ = √10

σ ≈ 3.2

That's not one of the answers, so let's try the standard deviation of a sample instead of a population.

Instead of dividing by n, we'll divide by n-1:

s² = 80 / 7

And take the square root:

s = √(80/7)

s ≈ 3.4

So that must be it.

6 0

3 years ago

What 2 numbers multiply to be -14 and add to be -3

Svetach [21]

Xy = -14
x + y = -3

$xy = -14$
$\frac{xy}{x} = \frac{-14}{x}$
$y = \frac{-14}{x}$

$x + y = -3$
$x + \frac{-14}{x} = -3$
$\frac{x^{2}}{x} + \frac{-14}{x} = -3$
$\frac{x^{2} - 14}{x} = -3$
$x^{2} - 14 = -3x$
$x^{2} + 3x - 14 = 0$
$x = \frac{-(3) \± \sqrt{(3)^{2} - 4(1)(-14)}}{2(1)}$
$x = \frac{-3 \± \sqrt{9 + 56}}{2}$
$x = \frac{-3 \± \sqrt{65}}{2}$
$x = \frac{-3 \± 8.06}{2}$
$x = -1.5 \± 4.03$
$x = -1.5 + 4.03$ $or$ $x = -1.5 - 4.03$
$x = 2.53$ $or$ $x = -5.53$

  x + y = -3
2.53 + y = -3
- 2.53 - 2.53
  y = -5.53
  (x, y) = (2.53, -5.53)

x + y = -3
  -5.53 + y = -3
+ 5.53   + 5.53
  y = 2.53
  (x, y) = (-5.53, 2.53)

The two numbers that multiply to -14 and add up to -3 are -5.53 and 2.53.

8 0

3 years ago

1: a 24 ounce box of cornflakes cost $4.59?

mestny [16]

The unit rate for the 1st one is: $0.19 / ounce

The unit rate for the 2nd one is: $0.16 / ounce

The 36 ounce box would be the better buy because it is less per ounce than the 24 ounce box

8 0

3 years ago

Read 2 more answers

A room is 8 meters wide and 5 meters long and 4 meters high. whats the volume of the room

nydimaria [60]

8 x 5 x 4 = 160m^3

to find the volume of a cube its V= W x H x L

3 0

2 years ago