Step-by-step explanation:
Sum of −8.46 and 5.31 means we need to add −8.46+5.31.
We know that,
|-8.46| > |5.31|
It means we subtract 8.46 - 5.31
At hundredth place, 6-1 = 5
At tenths place, 4-3 = 1
At ones place, 8-5 = 3
It would mean that, 8.46 - 5.31 = 3.15
8.46 has a negative sign. It means that the final answer will have negative sign i.e. −8.46+5.31 = -3.15
Hence, the correct option is (a) " Because |−8.46|>|5.31|, subtract |5.31| from |−8.46| and the sign is negative".
Step-by-step explanation:
Please refer to the attachment
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
Answer:
Step-by-step explanation:
50% = 0.5
(5 * 5) + (0.5 * 2) =
25 + 1 =
26 <===
20/21 is the answer to your problem.
