HI in the method I learnt for hypothesis testing, when doing critical region we divide the significance level by 2 then compare the lower tail value with that but for this question, it seems to be different, they compare the probability with the 1% instead of dividing it by 2 to get 0.5%, can anyone explain why they didn't compare with the 0.5% please?

3. It is known that on average 85% of seeds of a particular variety of tomato will germinate.

Ramesh selects 15 of these seeds at random and sows them.

i.

A. Find the probability that exactly 12 germinate.

[3]

B. Find the probability that fewer than 12 germinate.

[2]

The following year Ramesh finds that he still has many seeds left. Because the seeds are now

one year old, he suspects that the germination rate will be lower. He conducts a trial by

randomly selecting n of these seeds and sowing them. He then carries out a hypothesis test

at the 1% significance level to investigate whether he is correct.

ii. Write down suitable null and alternative hypotheses for the test. Give a reason for your

choice of alternative hypothesis.

[4]

iii. In a trial with n = 20, Ramesh finds that 13 seeds germinate. Carry out the test.

[4]

ALTERNATIVE METHOD – follow method above unless some mention of CR seen

Critical region method

LOWER TAIL

iv P(X ≤ 13) = 0.0219 > 1%

iv P(X ≤ 12) = 0.0059 < 1%

iv So critical region is {0,1,2,3,4,5,6,7,8,9,10,11,12}

iv 13 not in CR so not significant A1* Do not allow just ’13 not in CR’

iv

There is insufficient evidence to indicate that the proportion of seeds which have

germinated has decreased.

3. It is known that on average 85% of seeds of a particular variety of tomato will germinate.

Ramesh selects 15 of these seeds at random and sows them.

i.

A. Find the probability that exactly 12 germinate.

[3]

B. Find the probability that fewer than 12 germinate.

[2]

The following year Ramesh finds that he still has many seeds left. Because the seeds are now

one year old, he suspects that the germination rate will be lower. He conducts a trial by

randomly selecting n of these seeds and sowing them. He then carries out a hypothesis test

at the 1% significance level to investigate whether he is correct.

ii. Write down suitable null and alternative hypotheses for the test. Give a reason for your

choice of alternative hypothesis.

[4]

iii. In a trial with n = 20, Ramesh finds that 13 seeds germinate. Carry out the test.

[4]

ALTERNATIVE METHOD – follow method above unless some mention of CR seen

Critical region method

LOWER TAIL

iv P(X ≤ 13) = 0.0219 > 1%

iv P(X ≤ 12) = 0.0059 < 1%

iv So critical region is {0,1,2,3,4,5,6,7,8,9,10,11,12}

iv 13 not in CR so not significant A1* Do not allow just ’13 not in CR’

iv

There is insufficient evidence to indicate that the proportion of seeds which have

germinated has decreased.

Original post by Disha2504

HI in the method I learnt for hypothesis testing, when doing critical region we divide the significance level by 2 then compare the lower tail value with that but for this question, it seems to be different, they compare the probability with the 1% instead of dividing it by 2 to get 0.5%, can anyone explain why they didn't compare with the 0.5% please?

3. It is known that on average 85% of seeds of a particular variety of tomato will germinate.

Ramesh selects 15 of these seeds at random and sows them.

i.

A. Find the probability that exactly 12 germinate.

[3]

B. Find the probability that fewer than 12 germinate.

[2]

The following year Ramesh finds that he still has many seeds left. Because the seeds are now

one year old, he suspects that the germination rate will be lower. He conducts a trial by

randomly selecting n of these seeds and sowing them. He then carries out a hypothesis test

at the 1% significance level to investigate whether he is correct.

ii. Write down suitable null and alternative hypotheses for the test. Give a reason for your

choice of alternative hypothesis.

[4]

iii. In a trial with n = 20, Ramesh finds that 13 seeds germinate. Carry out the test.

[4]

ALTERNATIVE METHOD – follow method above unless some mention of CR seen

Critical region method

LOWER TAIL

iv P(X ≤ 13) = 0.0219 > 1%

iv P(X ≤ 12) = 0.0059 < 1%

iv So critical region is {0,1,2,3,4,5,6,7,8,9,10,11,12}

iv 13 not in CR so not significant A1* Do not allow just ’13 not in CR’

iv

There is insufficient evidence to indicate that the proportion of seeds which have

germinated has decreased.

3. It is known that on average 85% of seeds of a particular variety of tomato will germinate.

Ramesh selects 15 of these seeds at random and sows them.

i.

A. Find the probability that exactly 12 germinate.

[3]

B. Find the probability that fewer than 12 germinate.

[2]

The following year Ramesh finds that he still has many seeds left. Because the seeds are now

one year old, he suspects that the germination rate will be lower. He conducts a trial by

randomly selecting n of these seeds and sowing them. He then carries out a hypothesis test

at the 1% significance level to investigate whether he is correct.

ii. Write down suitable null and alternative hypotheses for the test. Give a reason for your

choice of alternative hypothesis.

[4]

iii. In a trial with n = 20, Ramesh finds that 13 seeds germinate. Carry out the test.

[4]

ALTERNATIVE METHOD – follow method above unless some mention of CR seen

Critical region method

LOWER TAIL

iv P(X ≤ 13) = 0.0219 > 1%

iv P(X ≤ 12) = 0.0059 < 1%

iv So critical region is {0,1,2,3,4,5,6,7,8,9,10,11,12}

iv 13 not in CR so not significant A1* Do not allow just ’13 not in CR’

iv

There is insufficient evidence to indicate that the proportion of seeds which have

germinated has decreased.

you only need to divide the significance level by 2 if it’s a two-tailed test (eg. when the alt hypothesis is ≠) but as you already know it’s lower tail, this is a one-tailed test so you don’t divide it

- How to do hypothesis testing
- GCSE
- Alevel Biology
- Hypothesis testing with critical values
- Hypothesis testing with critical values
- Hypothesis testing - Alevel Math AQA
- PMCC
- A level maths hypothesis tests
- confusion re: null hypothesis for population mean test
- Hypothesis testing with critical values
- Hypothesis testing
- AS Further Maths Statistics a (OCR MEI B)
- Studying AH statistics & prelim
- Applied Science Unit 3 investigation skills
- Central Limit Theorem: How do you calculate the test statistic?
- A Level Geography Edexcel NEA
- Hypothesis Testing
- Chemistry
- Edexcel a level maths
- Statistics Maths AS- Level help

Latest

Trending

Last reply 3 days ago

can someone please explain what principle domain is and why the answer is a not c?Maths

0

13