First, let’s break this down. What exactly are we looking at here? Well, Daisy measured the heights of 20 plants (in cm). The table, under Frequency, shows the # of plants that fit within a certain height range, shown on the left under Height of Plants (h).
Now, it says to take the midpoints of each group to figure out an estimate of the mean height. To find the mean, you add up all the totals and divide it by the # of items. So, let’s go through each row.
Midpoint of 0-10 is 5, and Frequency is 1, so that gives us 5.
Midpoint of 10-20 is 15, Frequency is 4, and 15x4=60.
We continue this with the other rows by finding the midpoint & multiplying the midpoint by the frequency (if the frequency is greater than 1). This gives us the numbers:
175 (25x7)
70 (35x2)
135 (45x3)
165 (55x3)
Now, we add these all together.
5+60+175+70+135+165=610
Finally, we divide 610 by the # of items (remember, there are 20 plants so we divide by 20) and 610/20 is 30.5.
FINAL ANSWER:
Thus, if I calculated correctly (which I hope I did lol), our estimate for the mean height of a plant is 30.5 cm!
I believe the correct answer is D ; 124.63ft^3. i apologize if it’s wrong!
Answer: her swimming speed = 1.875 mph
Speed of current = 0.625 mph
Step-by-step explanation:
Let x represent her swimming speed.
Let y represent the speed of the current.
Paulina swims 5 miles down a creek with a current for 2 hours. Since this is faster, it means that she swam with the current. Her total speed would be (x + y) mph
Distance = speed × time
Therefore,
5 = 2(x + y)
dividing both sides by 2, it becomes
2.5 = x + y- - - - - - -1
It takes her 4 hours to swim the same 5 miles back to her original destination against the
same current. It means that her total speed was (x - y) mph
Distance covered would be
5 = 4(x - y)
Dividing both sides by 4, it becomes
1.25 = x - y- - - - - - - 2
Adding equation 1 to equation 2, it becomes
3.75 = 2x
x = 3.75/2
x = 1.875
Substituting x = 1.875 into equation 1, it becomes
2.5 = 1.875 + y
y = 2.5 - 1.875
y = 0.625