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Vikentia [17]
3 years ago
14

How many two digit numbers have one odd digit and one even digit?

Mathematics
2 answers:
sineoko [7]3 years ago
3 0

Disclaimer: I'm assuming that you want any of the digit to be even, and the other to be odd, and not that you mean "the first digit odd and the second even".

You can note that there are 100 numbers with two digits, from 0 (which you can read as 00) to 99.

Now, we're only interested in those who have one odd digit and one even digit. Let's see if we can find a pattern in the numbers we do or don't want to include in our list:

Consider the numbers from 00 to 09. Since the first digit is zero, which is even, the unit digit must be odd. So, we must exlude the following numbers:

00, 02, 04, 06, 08

while the following numbers are ok:

01, 03, 05, 07, 09

Now, consider the numbers from 10 to 19. This time the first digit is one, which is odd, so the unit digit must be even. Now, we must exlude the following numbers:

11, 13, 15, 17, 19

while the following numbers are ok:

10, 12, 14, 16, 18

Can you see the pattern? If you consider any 10 consecutive numbers with the same first digit, you will always keep half of the numbers and discard the other half. In fact, if the first digit e is even, you will keep e1, e3, e5, e7 \text{ and } e9, while you will discard e0, e2, e4, e6 \text{ and } e8.

If, instead, the first digit o is odd, your choice will be the opposite: you will discard o1, o3, o5, o7 \text{ and } o9, while you will keep o0, o2, o4, o6 \text{ and } o8.

So, we've just proven that exactly half of the numbers with two digits have one odd digit and one even digit. We observed at the beginning that there are 100 two-digits number in total, so there are 50 numbers with one even digit and one odd digit.

sergiy2304 [10]3 years ago
3 0

Answer:

45 is the answer

Step-by-step explanation:

You might be interested in
Can you order this least to greatest, 385 km, 446,831 feet, 2,521,728 inches, 161,920 yards
loris [4]
To order these from the least to greatest you need to convert them all to one common unit of measurement. In this case I chose feet.
385 km= 1, 263, 123 ft
2, 521, 728 in= 210, 144 ft
161, 920 yards= 485, 760 ft
And of course 446, 831 feet equals itself. Now all you have to do is put them in the correct order!
Hope this helped :)
4 0
3 years ago
This question is confusing me
gizmo_the_mogwai [7]

Answer:

She went on the slide 8 times and on the roller coaster 4 times

Step-by-step explanation:

We convert each statements to a mathematical equation.

Firstly, let's represent the number of times she went on the coaster with R and the number of times on the slide with S. We know quite well she went on 12 rides. Hence the summation of both number of times yield 12.

Mathematically, R + S = 12. ........(i)

Now we also know her total wait time was 3hours. Since an hour equals 60 minutes, her total wait time would equal 180 minutes.

To get a mathematical representation for the wait time, we multiply the number of roller coaster rides by 25 and that of the slides by 10.

Mathematically, 25R + 10S = 180 .......(ii)

Here we now have two equations that we can solve simultaneously.

From equation 1 we can say R = 12 - S. We can then substitute this into equation 2 to yield the following:

25(12 - s) + 10s = 180

300 - 25s + 10s = 180

300 - 25s + 10s = 180

300 - 15s = 180

15s = 300 - 180

15s = 120

S = 120/15

S = 8

S = 8 , and R = 12 - S = 12 - 8 = 4

5 0
3 years ago
Can some one help me find the area? The arrows are just answers that could be right.
docker41 [41]
Area of circle=Πrsquare
A=Πx5x5
A=78.5
Area of rect 10x9=90
Tsurface =168.5
3 0
3 years ago
Y’all know this anything about this?
Andre45 [30]

We are given:

  • Parallelogram CDEF
  • ∠C = 13x - 10
  • ∠D = 5x + 10

To Find: ∠E

Concept Used:

  • Adjacent angles of a Parallelogram are Supplementary

Finding the value of 'x':

Since adjacent angles of a parallelogram are Supplementary:

∠D + ∠C = 180

5x + 10 + 13x - 10 = 180              [replacing the values of angle C and D]

18x = 180

x = 10                                          [dividing both sides by 18]

__________________________________________________________

Finding Measure of Angle D:

We are given that:

∠D = 5x + 10

∠D = 5(10) + 10                    [since x = 10]

∠D = 60°

__________________________________________________________

Finding the measure of ∠E:

∠D and ∠E are Adjacent angles

Since Adjacent angles are Supplementary:

∠D + ∠E = 180

60 + ∠E = 180

∠E = 120°                                  [subtracting 60 from both sides]

Hence, the measure of ∠E = 120°

7 0
2 years ago
What answer for not graph just solve it 5x + y = 2
Goryan [66]
Y=2-5x

or

y= .40 - x
6 0
3 years ago
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