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3 years ago

What is the doubling time of bacteria if you start with two bacteria and there are 128 bacteria after 3hrs?

Mathematics

1 answer:

iogann1982 [59]3 years ago

5 0

Answer:

B) 30min

Step-by-step explanation:

Start with 2 and continue to multiply that by 2 until you get 128

2 x 2 = 4

4 x 2 = 8

8 x 2 = 16

16 x 2 = 32

32 x 2 = 64

64 x 2 = 128

Then start with what you think could be the right answer based on how many intervals there are.

You know it can't be 15 because there definitely isn't enough and you know its not 1hr because theres way more than 3.

So you're left with either B) 30min or C) 45min

It has to be B) 30min because there are 6 intervals and 30min goes into an hour twice, meaning that if every 2 intervals is an hour there are 3 hours.

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What is 4 1/3= 1/3 x _/_ = 4 _/_

Oxana [17]

4 1/3 = 13/3 = 1/3 x 13/1 = 4 1/3

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3 years ago

What is the value of x in this diagram?

mixas84 [53]

Answer:

The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable, but we can work out its value if we try!

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2 years ago

A mattress store sells only king, queen and twin-size mattresses. Sales records at the store indicate that the number of queen-s

Nitella [24]

Answer:

The probability that the next mattress sold is either king or queen-size is P=0.8.

Step-by-step explanation:

We have 3 types of matress: queen size (Q), king size (K) and twin size (T).

We will treat the probability as the proportion (or relative frequency) of sales of each type of matress.

We know that the number of queen-size mattresses sold is one-fourth the number of king and twin-size mattresses combined. This can be expressed as:

$P_Q=\dfrac{P_K+P_T}{4}\\\\\\4P_Q-P_K-P_T=0$

We also know that three times as many king-size mattresses are sold as twin-size mattresses. We can express that as:

$P_K=3P_T\\\\P_K-3P_T=0$

Finally, we know that the sum of probablities has to be 1, or 100%.

$P_Q+P_K+P_T=1$

We can solve this by sustitution:

$P_K=3P_T\\\\4P_Q=P_K+P_T=3P_T+P_T=4P_T\\\\P_Q=P_T\\\\\\P_Q+P_K+P_T=1\\\\P_T+3P_T+P_T=1\\\\5P_T=1\\\\P_T=0.2\\\\\\P_Q=P_T=0.2\\\\P_K=3P_T=3\cdot0.2=0.6$

Now we know the probabilities of each of the matress types.

The probability that the next matress sold is either king or queen-size is:

$P_K+P_Q=0.6+0.2=0.8$

8 0

3 years ago

A boat travels for 7 hours. if it travels 4 hours downstream and 3 hours upstream. ten t covers a distance of 116 km. but if it

nadya68 [22]

Speed = Distance / Time
Distance = Speed*Time

For this problem, we should bear in mind that current speed has an impact on the boat speed...

for upstream, the boat goes against the current, and so its speed is

U = V - C

where V is the speed of the boat
C is the current speed

for downstream, it will be:

D = V + C

Convert the problem into mathematical equations:

4D + 3U = 116
3D + 4U = 108

4(V+C) + 3(V-C) = 116
4V + 4C + 3V -3C =116
7V + C = 116

3(V+C) + 4(V-C) = 108
3V + 3C + 4V - 4C = 108
7V - C = 108

Solving the equations:

7V + C = 116
7V - C = 108

14V = 224
V = 16km/hr —-> speed of boat

to get C:
7(16) + C = 116
C = 4km/hr

5 0

3 years ago

20x4 = blink so with u do is your put 20 group then u have add 4 to it

DENIUS [597]

Answer:

Thank you

Step-by-step explanation:

8 0

3 years ago