Grade 8 Exercise – Statistic & Probability
Answer the following questions.
1.
Look at the data below.
Based on the data above, construct:
a. Frequency table
b. Frequency polygon
c. Histogram
d. Stem-and-leaf diagram
Answer:
1
2.
A group of kids enrolled themselves into SMP Tunas Bangsa Gading Serpong. Mr. Fendy took
their data and created a frequency table based on their age as follows.
Find out the averages (mean, median and mode) and range of the data above.
Answer:
Mean =
(10 × 10)+(11 × 5)+(12 ×7) + (13 × 8)
Median =
(10+5+7+8)
𝑋15 + 𝑋16
2
=
11+12
2
=
343
30
= 11.43
= 11.5
Mode = 10
Range = 13 – 10 = 3
3.
Tunas Bangsa Gading Serpong helds physical checkup for their students. Below is the result
table of the height of grade 8 students.
Find out the averages (mean, median and mode) and range of the data above.
Answer:
Frequency
Midpoint
14
155
50
165
32
172.5
19
177.5
8
185
2
Total frequency = 123
Mean =
(14 × 155)+(50 × 165)+(32 × 172.5) + (19 × 177.5) +(8 ×185)
(14+50+32+19+8)
=
20792.5
123
= 169.04
Median = 𝑋𝑛+1 = 𝑋123+1 = 𝑋124 = 𝑋62 = 160 < h ≤ 170
2
2
2
Mode = 160 < h ≤ 170
Range = 190 – 150 = 40
4.
Find out the number of possible outcomes of:
a. tossing a coin thrice and rolling a dice twice.
Answer:
Possible outcomes of:
Tossing a coin thrice = 2³ = 8
Rolling a dice twice = 6² = 36
Tossing a coin thrice and rolling a dice twice = 8 x 36 = 288
b.
rolling a dice three times and picking a card.
Answer:
Rolling a dice thrice = 63 = 216
Picking a card = 52
rolling a dice three times and picking a card = 216 x 52 = 11 232
5.
Find out the probability of these following events.
a. Finding a number less than 3 when rolling a dice.
b. Getting two heads when tossing a coin 4 times.
c. Getting at least a head when tossing a coin 4 times.
d. Finding consonants in your complete name (write your own names first).
3
Answer:
a) P(getting two heads) =
6
16
b) P(getting at least a head) =
=
3
8
15
16
c) Name: Rachel Michaela
8
4
P(consonant) =
=
14 7
4
6.
Look at the picture of deck of card below
Black
Black
Red
Red
a.
Find out the probability of having black and picture card in one pick.
Answer:
P(black) =
26
52
P(picture) =
=
12
52
1
2
=
3
13
P(black and picture) =
b.
1
2
×
3
13
=
3
26
Find out the probability of having a red or number card in one pick.
Answer:
P(red) =
26
52
P(number) =
40
52
P(red with number) =
P(red or number) =
7.
20
52
26
52
+
40
52
-
20
52
=
46
52
=
23
26
Mrs. Bintang is hanging out outside her house and watches over the road. The probability she
sees a gojek bike is 0.7 and the probability she sees a grab bike is 0.85.
Work out the probability that she sees.
a. Both bikes
b. Neither bikes
5
Answer:
P (gojek bike) = 0.7
P (not gojek bike) = 1 – 0.7 = 0.3
P (grab bike) = 0.85
P (not grab bike) = 1 – 0.85 = 0.15
a. P(both bikes) = P(gojek and grab bikes)
= 0.7 x 0.85
= 0.595
b. P(neither bikes)
= P(not gojek and not grab bikes)
= 0.3 x 0.15
= 0.042
8.
A company made a regular dice but instead of putting numbers on each of its sides, they put
color. The colors were green, yellow, blue, white, orange and pink. They then tested the dice
by rolling it repetitively and below is the result.
a.
b.
Find out the regular probability for having green when rolling the dice.
Find out the experimental probability for having orange when rolling the dice.
Answer:
a) P(green) =
1
6
b) P(orange) =
12
50
=
6
25
6