Question

• Dhoni scored 8000 runs in a certain
number of innings. In the next five
innings, he was out of form and hence.
could inake only 85 runs, as a result hi
average reduced by l run. How many
innings did he play in total?​

Answer 1

Answer:

8000/n = a

8085/n+5 = a-1

n^2 + 90n – 40000 = 0

n = 160

n^2 + 5 = 165

Answer 2

Answer:

165 innings

Step-by-step explanation:

Let he scored 8000 runs in x innings,

$\text{Average}=\frac{\text{Total sum of observations}}{\text{Number of observations}}$

Thus, the average in x inning = $\frac{8000}{x}$

Now, he scored 85 runs in 5 innings,

So, his new average score = $\frac{8000+85}{x+5}$

According to the question,

$\frac{8000}{x}-1=\frac{8000+85}{x+5}$

$\frac{8000-x}{x}=\frac{8085}{x+5}$

$(8000-x)(x+5)=8085x$

$8000x+40,000-x^2-5x-8085x=0$

$x^2+90x-40000=0$

$x^2+250x-160x-40000=0$

$x(x+250)-160(x+250)=0$

$(x-160)(x+250)=0$

x = 160 or x = -250 ( not possible )

Hence, the number of inning played by him = 160 + 5 = 165