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Dimas [21]
3 years ago
10

in 2016 the members of a club paid a total of 42 in subscription fees.In 2017,the number of members were increased by 20 and the

subscription fees were subsequently reduced by 10 cents per member.the total of the subscription fees for 2017 was 45.How many members were there in 2016?
Mathematics
1 answer:
lianna [129]3 years ago
3 0

Answer:

70 members in 2016

Step-by-step explanation:

In 2016

Let the number of members= x

They all paid y amount

Total fees= 42

Xy= 42...... equation 1

In 2017

Members= x+20

They paid y-0.1

Total fees = 45

(X+20)(y-0.1)= 45…equation 2

Xy -0.1x +20y -2= 45

Using values from equation 1

42-0.1(42/y) +20y -2= 45

-4.2/y+20y-5= 0

20y² -4.2 -5y = 0

100y² -25y -21= 0

Solving quadratically

Y= 0.6 or -0.35

We are dealing with price so y Is

definitely a positive number

Y= 0.6

If y= 0.6

Solving for x

Xy= 42

X= 42/0.6

X=70

There were exactly 70 members in 2016

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2x-3-(x-1)

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The following histogram shows the height of 50 students of a class.
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Step-by-step explanation:

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Six measurements were made of the magnesium ion concentration (in parts per million, or ppm) in a city's municipal water supply,
lukranit [14]

Answer:

Option B is correct.

It is reasonable to believe that the mean magnesium ion concentration may be greater than 199.5 as the confidence interval obtained contains values that are greater than 199.5

Step-by-step explanation:

Complete Question

Six measurements were made of the magnesium ion concentration (in parts per million, or ppm) in a city's municipal water supply, with the following results. It is reasonable to assume that the population is approximately normal.

170 201 199 202 173 153

Based on a 95% confidence interval for the mean magnesium ion concentration, is it reasonable to believe that the mean magnesium ion concentration may be greater than 199.5? (Hint: you should first calculate the 95% confidence interval for the mean magnesium ion concentration.)

A) The likelihood cannot be determined.

B) Yes

C) No

Solution

For this question, obtaining the confidence interval will give a clear solution to the problem.

Since the Confidence Interval for the population mean is basically an interval of range of values where the true population mean can be found with a certain level of confidence, if the range obtained contains values greater than the standard we are comparing against (199.5), then the confidence interval proves that the mean magnesium ion may be greater than 199.5.

But to obtain the confidence interval, we need the mean and standard deviation for the sample.

170, 201, 199, 202, 173, 153

Mean = (sum of variables)/(total number of variables)

Sum of variables = 170+201+199+202+173+153 = 1098

Total number of variables = 6

Mean = (1098/6) = 183

Standard deviation = σ = √[Σ(x - xbar)²/N]

x = each variable

xbar = mean = 183

N = number of variables = 6

Σ(x - xbar)² = (170-183)² + (201-183)² + (199-183)² + (202-183)² + (173-183)² + (153-183)²

= 169 + 324 + 256 + 361 + 100 + 900

= 2110

σ = √(2110/6) = 18.75

Mathematically,

Confidence Interval = (Sample mean) ± (Margin of error)

Sample Mean = 183

Margin of Error is the width of the confidence interval about the mean.

It is given mathematically as,

Margin of Error = (Critical value) × (standard Error of the mean)

Critical value will be obtained using the t-distribution. This is because there is no information provided for the population mean and standard deviation.

To find the critical value from the t-tables, we first find the degree of freedom and the significance level.

Degree of freedom = df = n - 1 = 6 - 1 = 5.

Significance level for 95% confidence interval

(100% - 95%)/2 = 2.5% = 0.025

t (0.025, 5) = 2.57 (from the t-tables)

Standard error of the mean = σₓ = (σ/√n)

σ = standard deviation of the sample = 18.75

n = sample size = 6

σₓ = (18.75/√6) = 7.656

95% Confidence Interval = (Sample mean) ± [(Critical value) × (standard Error of the mean)]

CI = 183 ± (2.57 × 7.656)

CI = 183 ± 19.675

95% CI = (163.325, 202.675)

95% Confidence interval = (163.3, 202.7)

It is reasonable to believe that the mean magnesium ion concentration may be greater than 199.5 as the confidence interval obtained contains values that are greater than 199.5

Hope this Helps!!!

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Answer:

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Step-by-step explanation:


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