I'm guessing it is C because after you solve for n (you need to multiply the five over to isolate n), you get 20.
Answer:
total question =90
she obtained 75% of first 40 questions
- No. of question she got correct in first 40 = 75% * 40 = 30
2. in order to get 80% out of 90,
the no. of questions got correct by Ama = 80% * 90 = 72
3. As she already got 30 c0rrect in first 40 questions, the number of question she needs correct for remaining 50 = (72-30) = 42
percentage = 42/50*100% = 84%
Answer:
The estimate of a population proportion is approximately 541.
Step-by-step explanation:
We can solve the the problem by using the formula for minimum sample needed for interval estimate of a population proportion which is given by the formula
n = pq ((Z/2) / E)^2
As, p is not defined so we use the standard p and q which is 0.5 and 0.5.
The reason for this is we have to choose form 0.1 to 0.9 both values of p and q, we will find the maximum value of pq occurs when they both are 0.5.
Next, we will find the value of (Z/2) by looking at the Z-table, we will find that at 98% confidence (Z/2) = 2.326. Now we start substituting the values in the above formula
n = (0.5)×(0.5) × (2.326/0.05)^2
n = 541.027
n ≅ 541.
Ni : Zn: Cu = 7:2:9 =7x : 2x : 9x
7x+2x+9x = 3.8
18x=3.8
x=3.8/18=1.9/9≈0.21
Ni: 7x=7*0.21=1.47 ≈1.5 kg
Zn: 2x=2*0.21=0.42≈0.4 kg
Cu: 9x=9*0.21=1.89 ≈1.9 kg
Check 1.5+0.4+1.9 =3.8 True
