The answer is the first one.
Answer: 320 grams
Step-by-step explanation:
Let the mas of the teapot be denoted by a
Let the mass of the cups be denoted by c
The question can be turned into an equation which will be:
a + 4c = 1280 ......... equation i
a + 10c = 2720 ........ equation ii
Subtract equation i from ii
6c = 1440
c = 1440/6
c = 240 grams
The mas of the cup is 240 grams
From equation i
a + 4c = 1280
a + 4(240) = 1280
a + 960 = 1280
a = 1280 - 960
a = 320 grams
The mass of the teapot is 320 grams
You should use this method
Answer:
Step-by-step explanation:
Given that in a rural area, only about 30% of the wells that are drilled find adequate water at a depth of 100 feet or less.
The sample size n = 80
no of wells less than 100 feet deep=27
Sample proportion = 
a) Create hypotheses as

(Right tailed test)
p difference 
Std error of p = 
b) Assumptions: Each trial is independent and np and nq >5
c) Z test can be used.
Z= p diff/std error = 
p value = 0.233
d) p value is the probability for which null hypothesis is false.
e) Conclusion: Since p >0.05 we accept null hypothesis
there is no statistical evidence which support the claim that more than 30% are drilled.