The answer is A. 42
Solution:
Let x= ones digit, y=tens digit
1st condition (original number) : 7(x+y)=10y + x
2nd condition (new number by reversing the digits): 18+x+y=10x+y
simplifying:
1st condition: 6x=3y
2nd condition: x=2
substituting x=2 to 6x=3y
<span>y=4</span>
Using the binomial distribution, it is found that there is a 0.4096 = 40.96% probability that he answers exactly 1 question correctly in the last 4 questions.
<h3>What is the binomial distribution formula?</h3>
The formula is:


The parameters are:
- x is the number of successes.
- n is the number of trials.
- p is the probability of a success on a single trial.
Considering that there are 4 questions, and each has 5 choices, the parameters are given as follows:
n = 4, p = 1/5 = 0.2.
The probability that he answers exactly 1 question correctly in the last 4 questions is P(X = 1), hence:


0.4096 = 40.96% probability that he answers exactly 1 question correctly in the last 4 questions.
More can be learned about the binomial distribution at brainly.com/question/24863377
#SPJ1
Answer:
The second regon
Step-by-step explanation:
<span>The goal in simplifying numbers
is to reduce it that can be best seen in the eye. In here, you are given 5a²x(-3b²)x2c. Note that 5, -3 and 2 are
coefficients and a², b² and c are variables. Multiply first the coefficients 5, -3
and 2 and you get -30. Always remember that in multiplying numbers, especially
variables, the base of the exponent must be equal. However, you have variables
of a²,
b²
and, c. You cannot multiply or add them because they are different. So the
answer is -30a² b²c.</span>