Answer:
£0.40
Step-by-step explanation:
Divide £40 by £3.30 to find the number she can buy
£40 ÷ £3.30 = 12.1212..
That is she can buy 12 light bulbs
cost = 12 × £3.30 = £39.60
change = £40 - £39.60 = £0.40
Answer:
Mean = 78.2
Standard deviation = 5.8
Step-by-step explanation:
Mathematically z-score;
= (x-mean)/SD
From the question;
12% of test scores were above 85
Thus;
P( x > 85) = 12%
P(x > 85) = 0.12
Now let’s get the z-score that has a probability of 0.12
This can be obtained from the standard normal distribution table and it is = 1.175
Thus;
1.175 = (85 - mean)/SD
let’s call the mean a and the SD b
1.175 = (85-a)/b
1.175b = 85 - a
a = 85 - 1.175b ••••••••(i)
Secondly 8% of scores were below 70
Let’s find the z-score corresponding to this proportion;
We use the standard normal distribution table as usual;
P( x < 70) = 0.08
z-score = -1.405
Thus;
-1.405 =( 70-a)/b
-1.405b = 70-a
a = 70 + 1.405b ••••••(ii)
Equate the two a
70 + 1.405b = 85 - 1.175b
85 -70 = 1.405b + 1.175b
15 = 2.58b
b = 15/2.58
b = 5.81
a = 70 + 1.405b
a = 70 + 1.405(5.81)
a = 78.16
So mean = 78.2 and Standard deviation is 5.8
“Line graphs are useful in that they show data variables and trends very clearly and can help to make predictions about the results of data not yet recorded. They can also be used to display several dependent variables against one independent variable.”
“With a line graph, it is fairly easy to make predictions because line graphs show changes over a period of time. You can look at past performance in a line graph and make a prediction about future performance.”
Answer:
-2×h
Step-by-step explanation:
because it drops-2 by hour so multiply-2 by the difference of hours
Answer:
7) a= 20
8) m= 5
9)n = 5
10) b = 8
Step-by-step explanation:
7) 18+2=-2+2+a
>> 20 = a >> a = 20
18 + 2 = 20 so that isolates the variable leaving a = 20
8) -7+12 = m -12+12
>>> 5 = m >> m = 5
-7 + 12 = 5 so that again isolates the variable leaving m = 5
9) <u>-8(7</u> + <u>7n</u>) = -336
>> -56+56 + -56n = -336+56
>>> -56n/-56 = -280/-56
>>>> n = 5
use distributive property, cancel out necessary numbers, isolate the variable. leaving n = 5.
10) -140 = <u>-7(-4 </u>+ <u>3b)</u>
>> -140 = 28 - 21b >> -140-28 = -21b +28-28 ( flipped the numbers)
>>> -168/-21 = -21b /-21
>>>> 8 = b >> b =8
Hope it helps!
