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PilotLPTM [1.2K]
3 years ago
12

the sum of the digits of a certain two-digits number is 7.Reversing its digits increases the number by 9.What is the number

Mathematics
2 answers:
rusak2 [61]3 years ago
8 0
Unit digit=y
tens digit=x
the number: 10x+y

We suggest this system of equations:
x+y=7
(10y+x)=(10x+y)+9
we solve it by substitution method.
x=7-y
10y+(7-y)=(10(7-y)+y)+9
9y+7=70-10y+y+9
9y+10y-y=70+9-7
18y=72
y=72/18=4

x=7-y
x=7-4=3

number=10x+y=10*3+4=30+4=34

solution: the number: 34

To check:
3+4=7
43=34+9
dimaraw [331]3 years ago
7 0
The answer is 34. 3+4=7. 43-34=9. I hope this helps.
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Answer:

Null hypothesis: H0 = 0.50

Alternative hypothesis: Ha > 0.50

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Not more than half of all drivers drive a car made in this country

Rule

If;

P-value > significance level --- accept Null hypothesis

P-value < significance level --- reject Null hypothesis

Z score > Z(at 95% confidence interval) ---- reject Null hypothesis

Z score < Z(at 95% confidence interval) ------ accept Null hypothesis

Step-by-step explanation:

Given;

n= 200 represent the random sample taken

Null hypothesis: H0 = 0.50

Alternative hypothesis: Ha > 0.50

Test statistic z score can be calculated with the formula below;

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Where,

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n = Sample size = 200

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p^ = Observed proportion = 110/200 = 0.55

Substituting the values we have

z = (0.55-0.50)/√{0.50(1-0.50)/200}

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To determine the p value (test statistic) at 0.05 significance level, using a one tailed hypothesis.

P value = P(Z>1.414) = 0.0787

Since z at 0.05 significance level is between -1.96 and +1.96 and the z score for the test (z = 1.414) which falls within the region bounded by Z at 0.05 significance level. And also the one-tailed hypothesis P-value is 0.0787 which is greater than 0.05. Then we can conclude that we don't have enough evidence to FAIL or reject the null hypothesis, and we can say that at 5% significance level the null hypothesis is valid.

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3 years ago
If a circle has a diameter of 11.5 feet, what is the area?
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Answer:

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But before worrying about anything else, we must start the problem. Let's do that now.

The first step is to find the broken-down form of the area.

A = \frac{1}{4} \pi d^2

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