ACT · Mathematics

Statistics and probability

51 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 51 questions

The mean of five numbers is $25$ . Four of the numbers are $29, 29, 26, 23$ . What is the fifth number?
The mean of five numbers is $22$ . Four of the numbers are $16, 18, 17, 27$ . What is the fifth number?
The mean of five numbers is $20$ . Four of the numbers are $18, 22, 23, 16$ . What is the fifth number?
The mean of five numbers is $13$ . Four of the numbers are $15, 19, 15, 18$ . What is the fifth number?
The mean of five numbers is $26$ . Four of the numbers are $22, 32, 22, 22$ . What is the fifth number?
The mean of five numbers is $24$ . Four of the numbers are $21, 25, 21, 25$ . What is the fifth number?
What is the median of the data set $45, 12, 32, 54, 52$ ?
What is the median of the data set $33, 49, 8, 23, 16$ ?
What is the median of the data set $48, 11, 13, 8, 32$ ?
What is the median of the data set $31, 41, 14, 44, 13$ ?
A bag holds $5$ red, $8$ blue and $6$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $6$ red, $8$ blue and $1$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $7$ red, $3$ blue and $4$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $2$ red, $3$ blue and $6$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $8$ red, $5$ blue and $6$ green marbles. One marble is picked at random. What is the probability it is red?
The mean of five numbers is $27$ . Four of the numbers are $30, 29, 30, 25$ . What is the fifth number?
The mean of five numbers is $29$ . Four of the numbers are $32, 35, 26, 34$ . What is the fifth number?
The mean of five numbers is $22$ . Four of the numbers are $21, 28, 20, 18$ . What is the fifth number?
The mean of five numbers is $16$ . Four of the numbers are $11, 21, 15, 14$ . What is the fifth number?
The mean of five numbers is $20$ . Four of the numbers are $19, 26, 16, 22$ . What is the fifth number?
The mean of five numbers is $27$ . Four of the numbers are $25, 28, 26, 30$ . What is the fifth number?
What is the median of the data set $14, 59, 53, 37, 54$ ?
What is the median of the data set $50, 53, 4, 43, 30$ ?
What is the median of the data set $40, 35, 4, 51, 32$ ?
What is the median of the data set $39, 42, 36, 50, 59$ ?
A bag holds $8$ red, $6$ blue and $2$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $3$ red, $4$ blue and $5$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $7$ red, $3$ blue and $3$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $3$ red, $2$ blue and $6$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $6$ red, $2$ blue and $2$ green marbles. One marble is picked at random. What is the probability it is red?
The mean of five numbers is $20$ . Four of the numbers are $24, 26, 19, 14$ . What is the fifth number?
The mean of five numbers is $28$ . Four of the numbers are $29, 27, 32, 23$ . What is the fifth number?
The mean of five numbers is $18$ . Four of the numbers are $14, 13, 24, 21$ . What is the fifth number?
The mean of five numbers is $14$ . Four of the numbers are $9, 9, 12, 12$ . What is the fifth number?
The mean of five numbers is $13$ . Four of the numbers are $10, 19, 12, 14$ . What is the fifth number?
The mean of five numbers is $22$ . Four of the numbers are $22, 21, 25, 21$ . What is the fifth number?
What is the median of the data set $32, 8, 36, 49, 9$ ?
What is the median of the data set $22, 29, 38, 25, 52$ ?
What is the median of the data set $31, 49, 55, 10, 57$ ?
What is the median of the data set $32, 46, 53, 39, 25$ ?
A bag holds $7$ red, $6$ blue and $6$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $7$ red, $8$ blue and $3$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $7$ red, $3$ blue and $5$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $7$ red, $3$ blue and $6$ green marbles. One marble is picked at random. What is the probability it is red?
A bag holds $7$ red, $5$ blue and $2$ green marbles. One marble is picked at random. What is the probability it is red?
The mean of $6$ test scores is $82$ . After the lowest score is removed, the mean of the remaining $5$ scores is $85$ . What was the lowest score?
Of $100$ students, $55$ are in band, $40$ are in chorus and $20$ are in both. A student who is not in chorus is chosen at random. What is the probability that this student is in band?
The mean of $6$ test scores is $82$ . A seventh score is added and the mean becomes $84$ . What is the seventh score?
The data set $3, 7, 9, x, 15$ has a median of $8$ . What is the mean of the data set?
A bag has $5$ red marbles and $3$ blue marbles. Two marbles are drawn without replacement. What is the probability that at least one is red?
A data set has mean $50$ and standard deviation $8$ . Each value is multiplied by $2$ , and then $5$ is subtracted. What are the new mean and standard deviation?

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