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slava [35]
4 years ago
11

Here is a number machine.

Mathematics
1 answer:
Ket [755]4 years ago
5 0

Answer:

a) 37

b) 9

Step-by-step explanation:

(The input) × 5 - 3 = (The output)

When the input is 8,

8 × 5 - 3

= 40 - 3

= 37

When the output is 42.

(The input) × 5 - 3 =42

(The input) × 5 = 42 + 3

(The input) × 5/5=45/5

(The input) = 9

The input was 9.

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if it takes 60 minutes for 9 people to paint 5 walls thhen how many minutes does it take for 4 people to paint 6 walls
adoni [48]

--  9 people paint 5 walls in 60 minutes

--  9 people paint (5 / 5) = 1 wall in (60 / 5) = 12 minutes

--  (9 / 9) = 1 person paints 1 wall in (9 x 12) = 108 minutes

-- 1 person paints (1 x 6) = 6 walls in (108 x 6) = 648 minutes

-- (1 x 4) = 4 people paint 6 walls in (648 / 4) = 162 minutes .
 
8 0
4 years ago
Read 2 more answers
The sum of three numbers is 124. The third number is 3 times the first. The second number is 9 more than the first. What are the
Leona [35]

Answer:

23, 32, 69

Step-by-step explanation:

3 numbers x, y, z

z = 3x

y = x + 9

x+y+z=124

x + (x + 9) + 3x = 124

5x + 9 = 124

5x = 115

x = 23

y = 32

z = 69

check: 23 + 32 + 69 = 124

8 0
4 years ago
The distance around a circle is 37.7 meters long. what is the diameter of the circle?
aksik [14]
Ok so we know that the distance around the circle (or circumference) is equal to the diameter times pi.
This means that
37.7 = \pi \times d
d being the diameter,

This means that:
d =  \frac{37.7}{\pi}
= 12.00028271
= 12 m

So the diameter of the circle is 12 metres.

Hope this helped
6 0
4 years ago
Find the missing length indicated.
Aneli [31]
I can tryyyyyyyyyyyyyyyyyyy
8 0
4 years ago
The probability distribution of the number of students absent on Mondays, is as follows: X 0 1 2 3 4 5 6 7 f(x) 0.02 0.03 0.26 0
alexgriva [62]

a) Add up all the probabilities f(x) where x>3:

f(4)+f(5)+f(6)+f(7)=0.35

b) The expected value is

E[X]=\displaystyle\sum_xx\,f(x)=3.16

Since X is the number of absent students on Monday, the expectation E[X] is the number of students you can expect to be absent on average on any given Monday. According to the distribution, you can expect around 3 students to be consistently absent.

c) The variance is

V[X]=E[(X-E[X])^2]=E[X^2]-E[X]^2

where

E[X^2]=\displaystyle\sum_xx^2\,f(x)=11.58

So the variance is

V[X]=11.58-3.16^2\approx1.59

The standard deviation is the square root of the variance:

\sqrt{V[X]}\approx1.26

d) Since Y=7X+3 is a linear combination of X, computing the expectation and variance of Y is easy:

E[Y]=E[7X+3]=7E[X]+3=25.12

V[Y]=V[7X+3]=7^2V[X]\approx78.13

e) The covariance of X and Y is

\mathrm{Cov}[X,Y]=E[(X-E[X])(Y-E[Y])]=E[XY]-E[X]E[Y]

We have

XY=X(7X+3)=7X^2+3X

so

E[XY]=E[7X^2+3X]=7E[X^2]+3E[X]=90.54

Then the covariance is

\mathrm{Cov}[X,Y]=90.54-3.16\cdot25.12\approx11.16

f) Dividing the covariance by the variance of X gives

\dfrac{\mathrm{Cov}[X,Y]}{V[X]}\approx\dfrac{11.16}{1.59}\approx0.9638

5 0
3 years ago
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