Using step-deviation method, calculate the mean marks of the foll… - Vidyadip

Question

Using step-deviation method, calculate the mean marks of the following distribution

Class Interval	$50 - 55$	$55 - 60$	$60 - 65$	$65 - 70$	$70 - 75$	$75 - 80$	$80 - 85$	$85 - 90$
Frequency	$5$	$20$	$10$	$10$	$9$	$6$	$12$	$8$

✓

Answer

$\therefore \text { Mean } X = A +\frac{\sum f \cdot u}{\sum f} \times i \quad .[ i =\text { length of C.I. }] $
$ =67.5+\frac{24}{80} \times 5$
$ =67.5+1.5 $
$ =69 .$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "[5 marks sum]" from Statistics→Statistics — all question types→Mathematics STD 10 question papers→ICSE Board STD 10 question papers→ICSE Board question paper generator→

Similar questions

Draw line segments OA = 4.5 cm, OB = 3.2 cm such that ∠ AOB = 45°. Construct a circle touching OA at A and passing through B.

From the following cumulative frequency table , find :
Median ,Lower quartile ,Upper quaetile

Marks$($less than$)$	$10 $	$20$	$30$	$40$	$50$	$60$	$70$	$80$	$90$	$100$
Cumulative frequency	$5$	$24$	$37$	$40$	$42$	$48$	$70$	$77$	$79$	$80$

Divide Rs 50,760 into two parts such that if one part is invested in 8% Rs 100 shares at 8% discount and the other in 9% Rs 100 shares at 8% premium, the annual incomes from both the investments are equal.

The height and radius of base of a cylinder area in the ratio $3: 1$. if it volume is $1029 \ cm ^3$; find it total surface area.

In the adjoining figure, O is the centre of the circle and AB is a tangent to it at point B. ∠BDC = 65° Find ∠BAO.

Calculate the amount and the compound interest for the following:
Rs. 16,000 at $15 \%$ p.a. in $2 \frac{2}{3}$ years

Mr Shameem invested 33 1/3% of his savings in 20% Rs 50 shares quoted at Rs 60 and the remainder of the savings in 10% Rs 100 share quoted at ₹ 110. If his total income from these investments is Rs 9,200; find :
(1) his total savings
(2) the number of Rs 50 share
(3) the number of Rs 100 share

The angles of elevation of the top of a tower from two points A and B at a distance of a and b respectively from the base and in the same straight line with it are complementary. Prove that the height of the tower is $\sqrt{a b}$.

Ankita started paying Rs 400 per month in a 3 years recurring deposit. After six months her brother Anshul started paying Rs 500 per month in a $2 \frac{1}{2}$ years recurring deposit. The bank paid $10 \%$ p.a. simple interest for both. At maturity who will get more money and by how much?

Prove the following identitie:
$\cot ^2 A\left(\frac{\sec A-1}{1+\sin A}\right)+\sec ^2 A\left(\frac{\sin A-1}{1+\sec A}\right)=0$