Question

Two friends Richa and Sohan have some savings in their piggy bank. They decided to count the total coins they both had. After counting they find that they have fifty * 1 coins, forty eight * 2 coins, thirty six ? 5 coins, twenty exght 10 coins and eight ? 20 coins. Now, they said to Nisha, their another friends, to choose a coin randomly. Find the probability that the coin chosen is

1) 5 rupee coin
2) 20 rupee coin
3) not a 10 rupee coin
4) of denomination of atleast 10rupee
5) of denomination of atmost 5 rupee​

Answer 1

Answer:

Total number of coins = 50 + 48 + 36 + 28 + 8 = 170

(i) (c): Number of ₹ 5 coins = 36

Required probability = 3670=1885

(ii) (b): Number of ₹20 coins = 8

Required probability = 8170=485

(iii) (d): Number of ₹10 coins = 28

Probability (coin is of ₹10) = 28170

Required probability = 1 - P(coin is of 10)

=1−28170=142170=7185

(iv) (a) : Total number of coins of ₹10 and ₹ 20

= 28 + 8 = 36

Required probability = 36170=1885

(v) (a): Total number of coins of ₹1, ₹2 and ₹ 5

= 50 + 48 + 36 = 134

Step-by-step explanation:

Answer 2

Given: Fifty * 1 coins, forty eight * 2 coins, thirty six * 5 coins, twenty eight * 10 coins and eight * 20 coins.

To find: The probability that the coin chosen is,

(1)  5 rupee coin

(2) 20 rupee coin

(3) not a 10 rupee coin

(4) of denomination of atleast 10rupee

(5) of denomination of atmost 5 rupee​

Solution:

• Probability (represented by P(E))is the number of favourable outcomes divided by the number of possible out comes.
• There are a total of 170 coins, so the number of possible outcomes is 170.

(1)

• The number of favourable outcomes is 36, since the number of 5 rupee coins is 36.

        $P(E) = \frac{36}{170}$

                  $= \frac{18}{85}$

(2)

• The number of favourable outcomes is 8, since the number of 20 rupee coins is 8.

       $P(E) = \frac{8}{170}$

                 $= \frac{4}{85}$

(3)

• The number of favourable outcomes is 142, since the number of coins that are not 10 rupee coins is 142.

        $P(E) = \frac{142}{170}$

                  $= \frac{71}{85}$

(4)

• The number of favourable outcomes is the sum of 162 and 170, since the number of coins upto 10 rupee is 162 and the number of coins upto 20 rupee is 170.

        $P(E) = \frac{162}{170} + \frac{170}{170}$

                  $= \frac{166}{85}$

(5)

• The number of favourable outcomes is 134, since the number of coins that are of denomination of atmost 5 rupee coins is 134.

       $P(E) = \frac{134}{170}$

                 $= \frac{67}{85}$

Therefore, the probability that the coin chosen is,

(1) 5 rupee coin is 18/85.

(2) 20 rupee coin is 4/85.

(3) not a 10 rupee coin is 71/85.

(4) of denomination of atleast 10 rupee is 166/85.

(5) of denomination of atmost 5 rupee​ is 67/85.