Answer:
c.
Step-by-step explanation:
Hello!
To take a sample to estimate the mean height of all students at a university and that the value you reach is statistically valid you need the sampling method to be random and representative of the whole population, in this example, all university students.
a. Measure the heights of 50 students found in the gym during basketball intramurals.
This method is not the best because you would be sampling only basketball players leaving all other students of the university outside, i.e. your sample will not be representative of all the students, just the ones that play basketball.
b. Measure the heights of all engineering majors.
This method is not good, the sample only represents engineering mayors meaning that it does not include the students of any other subjects.
c. Measure the heights of the students selected by choosing the first name on each page of the campus phone book.
With this method you choose students regardless of the sport or major they're are taking, it is more representative of the population of university students, of the three options, this is the best one.
I hope it helps!
Answer:
6kg pure copper and 30 kg 10% copper was mixed to give 36kg of 25% alloy
Step-by-step explanation:
Here, we want to produce 36 kg of 25% alloy
Let the Pure copper be x kg while 10% alloy be y kg
Pure copper is simply 100% copper
Thus;
x + y = 36 •••••(i)
Then;
100% of x + 10% of y = 25% of 36
= x + 0.1y = 9 •••••• ii)
From i x = 36-y
from ii, x = 9-0.1y
Equate both x
36-y = 9-0.1y
36-9 = 0.1y + y
0.9y = 27
y = 27/0.9
y = 30
x = 36-y
x = 36-30
x = 6 kg
Answer:
Step-by-step explanation:
x = 136/2 = 68°
The frame of film is actually 50 mm high, but it looks 16 m high on the screen.
Remember that 1 m = 1,000 mm.
So everything looks (16,000)/(50) = <u>320 times</u> as big on the screen
as it is on the film. That's called the scale factor.
The penguin is 35 mm high on the film. He'll look 320 times bigger on the screen.
(320) x (35 mm) = 11,200 mm = <u>11.2 meters</u> high
