we know that
One tens is equal to the number----------->
so
tens is equal to
therefore
<u>the answer is</u>
A girl had 20 coins in nickels and dimes whose sum was $1.40. She spent 65cents , using 8 coins. She now has ? nickels.
2 answers:
Answer:
9 Nickles
Step-by-step explanation:
Let n = number of nickles and d = number of dimes
d + n = 20 -----------(1) [ total number of coins 20 ]
Dimes = $0.10
Nickles = $0.05
0.1d + 0.05n = $1.40 ---------- (2) [20 coins worth $1.40]
Since d + n = 20
∴ n = 20 - d
Let's substitute n in equation (2)
0.1d + 0.05(20-d) = 1.40
0.1d + 1 - 0.05d = 1.40
0.1d + 0.05d = 1.40 - 1
0.05d = 0.4
d =
d = 8
Now put value of d in equation (1)
n + 8 = 20
n = 20 - 8
n = 12
Let's check 8(0.1) + 12(0.05) = $1.40
Now she spent 65 cents using 8 coins.
The only combination of 8 coins worth $0.65 is
5d + 3n = $0.65
Hence, she used 5 dimes and 3 nickles.
Now she has 12 - 3 = 9 Nickles
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Answer:
a.
b.
E of first can =
E of second can =
c. Yes
Step-by-step explanation:
The efficiency ratio is:
E = Surface Area / Volume
a.
We can write:
Where
S is surface area of cylinder
V is volume of cylinder
The formulas are:
S =
V =
So, the <u>efficiency ratio (E) </u>is:
b.
The first can has radius "r" and height "h", so the efficiency ratio is:
The second can has same height, "h", and twice radius, "2r", so the efficiency ratio becomes:
c.
We now need to say if the company made a good decision or not.
If you look at both the Efficiency ratios above, you will see that the difference is in the numerator.
The first can has "2h"
The second can has "h"
The "2h" makes the numerator for the first can BIGGER than the "h" of the second can, so the Efficiency ratio of first can is thus, BIGGER.
We need smaller ratio.
So, 2nd can has indeed smaller ratio, so the company made a good decision.