The sum of two numbers is 21. The difference between them is 5. What are the two numbers?

Mathematics

1 answer:

Nata [24]3 years ago

5 0

Answer: 13 and 8

Step-by-step explanation:

13+8=21

13-8=5

All I did was trial and error. Plus, it helps to set up an equation : x+x=21, x-x=5

You might be interested in

Ber [7]

A. 7x

B. 8x-1

C. 6x+12

D. 3x +4

E. 13x-7

6 0

3 years ago

Which pair of numbers is relatively prime?

Vladimir [108]

I think it is 21 and 50. The only common factor they have is 1.

All the others are divisible by 1 & 3.

3 0

3 years ago

Read 2 more answers

Discrete R.V. Assume a student shows up for EGR 280 completely unprepared and the instructor gives a pop quiz. Assume there are

Tom [10]

Answer:

a) p=0.2

b) probability of passing is 0.01696

c) The expected value of correct questions is 1.2

Step-by-step explanation:

a) Since each question has 5 options, all of them equally likely, and only one correct answer, then the probability of having a correct answer is 1/5 = 0.2.

b) Let X be the number of correct answers. We will model this situation by considering X as a binomial random variable with a success probability of p=0.2 and having n=6 samples. We have the following for k=0,1,2,3,4,5,6

$P(X=k) = \binom{n}{k}p^{k}(1-p)^{n-k} = \binom{6}{k}0.2^{k}(0.8)^{6-k}$ .

Recall that $\binom{n}{k}= \frac{n!}{k!(n-k)!}$ In this case, the student passes if X is at least four correct questions, then

$P(X\geq 4) = P(X=4)+P(X=5)+P(X=6)=\binom{6}{4}0.2^{4}(0.8)^{6-4}+\binom{6}{5}0.2^{5}(0.8)^{6-5}+\binom{6}{6}0.2^{6}(0.8)^{6-6}= 0.01696$

c)The expected value of a binomial random variable with parameters n and p is $E[X] = np$ . IN our case, n=6 and p =0.2. Then the expected value of correct answers is $6\cdot 0.2 = 1.2$