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3 years ago

How many 9 digit combinations with 10 numbers?

1 answer:

3 0

There are 1 billion 9 digit numbers (000,000,000 through 999,999,999). There are 45 different combinations of two different numerals (10 x 9 divided by 2). There are 512 (2 to the 9th power) different permutations for any two numbers to be used in a 9 digit number

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At 3:30 p.m., Berto’s train was 34 miles past the egg farm, traveling at an average speed of 85 miles per hour. At the same time

timurjin [86]

E=egg farm

x=distantce between the Berto´s trains and the meeting point.

t=time where the trains meet up

⇒110 miles/h ⇒85miles/h

[---------------------------E----------------------]-------------------------------------X

[............12 miles.......][........34 miles.....][------------ x ----------------------]

distance between Berto´s train and Eduardo´s train=

=12 miles+34 miles=46 miles.

S=d/t ⇒d=S*t

S=seed

d=distance

T=time

Eduardo´s train;

46 miles+x=t*110 miles/h ⇒x=t*110 miles/h-46 miles (1)

Berto´s train;

x=t*85 miles/h (2)

With the equations (1) and (2) we suggest this system equations:

x=t* 110 miles/h-46 miles

x=t*85 miles/h

we solve this system equiations :

t*110 miles/h-46 miles=t*85 miles/h

110t miles/h-85t miles/h=46 miles

25 t miles/h=46 miles

t=46 miles/25 miles/h=1,84 hour (≈1 hour, 50 minutes, 24 seconds)

x=t*85 miles/h=156,4 miles

Solution: 1,84 hour

3 0

3 years ago

Read 2 more answers

Estimate 40% of 128 Please help :c

Ivanshal [37]

Answer:

51.2 is 40% of 128

Step-by-step explanation:

3 0

3 years ago

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The amount A of the radioactive element radium in a sample decays at a rate proportional to the amount of radium present. Given

slavikrds [6]

Answer:

a) $\frac{dm}{dt} = -k\cdot m$ , b) $m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }$ , c) $m(t) = 10\cdot e^{-\frac{t}{2438.155} }$ , d) $m(300) \approx 8.842\,g$

Step-by-step explanation:

a) Let assume an initial mass m decaying at a constant rate k throughout time, the differential equation is:

$\frac{dm}{dt} = -k\cdot m$

b) The general solution is found after separating variables and integrating each sides:

$m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }$

Where $\tau$ is the time constant and $k = \frac{1}{\tau}$

c) The time constant is:

$\tau = \frac{1690\,yr}{\ln 2}$

$\tau = 2438.155\,yr$

The particular solution of the differential equation is:

$m(t) = 10\cdot e^{-\frac{t}{2438.155} }$

d) The amount of radium after 300 years is:

$m(300) \approx 8.842\,g$

4 0

3 years ago

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The graph above shows the cost of a large pizza

madreJ [45]

I would say the first choose that the vertical axis should use $0.50 intervals instead of $1.
Because this would make it much easier to read and understand and would it would also be more accurate.

5 0

3 years ago

Jose asks his friends to guess the higher of two grades he received on his math tests. He gives them two hints. The difference o

denis23 [38]

Option D. 96 is the correct answer.

Explanation:

Let the higher grade be = x

Let the lower grade be = y

As given, The difference of the two grades is 16

$x-y=16$ or $x=16+y$ .... (1)