Question
Using the step-deviation method, find the mean from the following data :
| $x_i$ | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
| $f_i$ | 170 | 320 | 530 | 700 | 230 | 140 | 110 |
✓
Answer
20.62
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
On a certain sum, the compound interest in $2$ years amounts to$\text{ Rs.} 4,240.$ If the rate of interest for the successive years is $10\%$ and $15\%$ respectively, find the sum.
→What are rational numbers? Give ten examples.
Factorise : $4xy - x^2- 4y^2+ z^2$
→If $m=\frac{1}{3-2 \sqrt{2}}$ and $n=\frac{1}{3+2 \sqrt{2}}$, find $m^2$
→Solve for $\mathbf{x}: 4^{x-1} \times(0.5)^{3-2 x}=\left(\frac{1}{8}\right)^{-x}$
→Write three rational numbers between $\sqrt{3}$ and $\sqrt{5}.$
→If $(3 a+4 b)=16$ and $a b=4$, find the value of $\left(9 a^2+16 b^2\right)$.
→
Two circles touch externally. The sum of their areas is 117$\pi$ $cm ^2$ and the distance between their centres is 15 cm. Find the radii of the two circles.
[Hint. $\pi R_1^2+\pi R_2^2=117 \pi \Rightarrow R_1^2+R_2^2=117$. Also, $R_1+R_2=15$.$
\begin{array}{c}
\left(R_1+R_2\right)^2=(15)^2 \Rightarrow\left(R_1^2+R_2^2\right)+2 R_1 R_2=225 \Rightarrow R_1 R_2=\frac{(225-117)}{2}=54 . \\
\therefore\left(R_1-R_2\right)^2=\left(R_1+R_2\right)^2-4 R_1 R_2=(15)^2-4 \times 54=(225-216)=9
\end{array}
$
Now, solve : $R_1+R_2=15$ and $R_1-R_2=3$ ]
If $4 \cot \theta=3$, show that $\left(\frac{\sin \theta-\cos \theta}{\sin \theta+\cos \theta}\right)=\frac{1}{7}$.
→If $\frac{\sqrt{3}+1}{\sqrt{3}-1}=a+b \sqrt{3}$, find the values of $a$ and $b$.
→