All categories

3 years ago

How many 3 letter codes are possible using a-j without repeats?

1 answer:

5 0

There are 10 letters in the set {a, b, c, d, e, f, g, h, i, j} which is the pool of letters to choose from when making these three letter codes.

We have 10 choices for slot 1
Then 9 choices for slot 2. This is because we can't reuse the choice for slot 1
Then 8 choices for slot 3

Overall, there are 10*9*8 = 90*8 = 720 different permutations

Answer: 720

Note: you can use the nPr permutation formula with n = 10 and r = 3 to get the same answer

You might be interested in

How many balls can Michael predict to hit if he is pitched 20 balls?

Vinvika [58]

If Michael is pitched 20 balls he will at least hit ten of them!

7 0

3 years ago

The speeds of vehicles traveling on a highway are normally distributed with a population standard deviation of 7 miles per hour

True [87]

Answer: $(56.03\ ,63.97)$

Step-by-step explanation:

Given : The speeds of vehicles traveling on a highway are normally distributed .

Standard deviation: $\sigma: 7$

Since , sample size : $n=20$ , which is small sample (n<30) so the test applied here is a t-test.

Degree of freedom= $n-1=20-1=19$

Sample mean : $\overline{x}=60$

Level of significance : $1-\alpha:0.98$

Then , significance level : $\alpha: 1-0.98=0.02$

Using t-distribution table , Critical value : $\text{t-score}=t_{n-1, \alpha/2}= 2.539483$

The confidence interval for population mean is given by :-

$\overline{x}\pm t_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}$

$60\pm( 2.539483)\dfrac{7}{\sqrt{20}}\approx60\pm3.97=(56.03\ ,63.97)$

Hence, a 98% confidence interval for the population mean= $(56.03\ ,63.97)$

4 0

3 years ago

An eight character password uses four digits 1-6 and four letters A-Z with repeats allowed. How many possible passwords like thi

Ratling [72]

4 x 8 x 6 x 4 x 26 = 19,968

i think however, i could be wrong. my teacher told me to use the fundamental counting principle. you multiply each different part of the problem.

3 0

4 years ago

At 2:15 PM, the temperature of a substance in a science experiment was 7∘F. The temperature was then recorded at 15-minute inter

Alja [10]

I honestly don’t know

3 0

4 years ago

The yummy chocolate company sold 2 3/4 pounds of milk chocolate on Saturday and 2 7/8 pounds of milk chocolate on Sunday how muc

Likurg_2 [28]

Answer: 5 5/8
Reasoning:

Find the similar denominator between the two fractions, in this case it’s 8. The number 4 can get to 8 by multiplying by 2 so you multiply it by 2 also with the numerator. Add together and you have an improper fraction, if you convert it into a mixed fraction you should get 5 5/8

8 0

3 years ago