Question

find the mean of first 25 multiplies of 5​

Answer 1

Answer:

Method 1: The average = 5(1+25)/2 = 5*13 = 65.

Method 2. Sum of 25 terms of an Ap whose first term is 5 and common difference = 5 is

S25 = (25/2)[2*5 + (25–1)*5]

= (25/2)[10+24*5]

= (25/2)[10+120]

= 25*130/2

= 1625

So average of the 25 terms is 1625/25 = 65.

Method 3: Among 25 terms, the middle term will be the 13th term from either end and it will be the average of the whole series. The 13th term is 5x13 = 65.

So the average of the 25 terms which are multiples of 5 is 65.

Answer 2

Answer:

5+10+15+20+25+30+35+40+45+50+55+60+65+70+75+80+85+90+95+100+105+110+115+120+125= 1625

mean = 1625÷25 = 65

Step-by-step explanation:

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