Question

The table shows a frequency distribution of the life time of $400$ radio tubes tested at a company.

Life time (hours)	Number of tubes	Life time (hours)	Number of tubes
$300-399$	$14$	$800-899$	$62$
$400-499$	$46$	$900-999$	$48$
$500-599$	$58$	$1000-1099$	$22$
$600-699$	$76$	$1100-1199$	$6$
$700-799$	$68$
			Total $400$

Column $II$ gives data for description given in column $I$, match them correctly.

Answer 1

No.	Lifetime (hours)	No. of tubes
1	300-399	14
2	400-499	46
3	500-599	58
4	600-699	76
5	700-799	68
6	800-899	62
7	900-999	48
8	1000-1099	22
9	1100-1199	6
	Total	400

A) Upper limit of fifth class - 4) $799$

B) Lower limit of eighth class - 3) $1000$

C) Class marks of seventh class = $\frac{upperlimit+lowerlimit}{2}$

= $\frac{900+999}{2}$ = $949.5$

2) $949.5$

D) Clas Interval Size = Upper limit - lower limit + 1

=$399-300+1$

= $100$