The answer according to key is A but I am unable to understand how

## 3 Answers

(1) Imagine the six other people standing in a line

o   o   o   o   o   o

Now there are seven possible spots where you can put the four others

_ o _ o _ o _ o _ o _ o _

You can put multiple of them into the same spot, for example

A o   o BCo   o   o D o

If you condense this and compare this to some other examples

AooBCoooDo
ooAoBoooCD
oABCooDooo

(2) You can see we essentially have **10 people** in a row, and we're choosing **which** of these ten people are ABCD
In this I am trying to mathematically resolve how to depict the required scenario of ABCD in Permutation and/or Combination as if we try to put it in cases, it would take 10!/6! cases. Thus i am trying to figure a way out to represent the cases using P&C but I can't figure a way to do it. Other than that it is simple to fill the gaps with 6 people by Permutation but I am unable to figure out a way to put the ABCD restriction and as a result I am unable to solve the question.
*(Edit: see new comment)*

## Related questions

0 like 0 dislike
0 answers
"Previous comparison of change in CAPS score between sertraline and placebo showed effect sizes of 0.31 and 0.37 (ref. 16). Similarly, comparison of change in CAPS score ...
0 like 0 dislike
1 answer
Are the S3/S4 Edexcel Further Maths units useful to become an actuary? Topics include sampling, unbiased and biased estimators, confidence intervals and significance test...
0 like 0 dislike
3 answers
Received two job offers. I wish I would've taken the other job. Can I go back to the company I turned down?
0 like 0 dislike
6 answers
Quitting job possibly to work on mental health issues but gap in employment could affect job prospects in the future
0 like 0 dislike
2 answers
I did this all wrong but got the right answer? Took half of .075, used d=(1+i)/i to get discount rate, and just added. Decimal was off, but i got the numbers right. Luck?...